Remove local copies of websockify

Replace custom getPosition algorithms with getBoundingClientRect.

Closes #434

The current noVNC release is 0.5.1, but package.json still
says version 0.5.0.  This fixes that.

Fixes #441

This commit removes local copies of websockify.
Instead `utils/launch.sh` performs the following logic:

If `utils/websockify` exists, use `utils/websockify/run` (if the latter
does not exist, or is not executable, fail, since this is probably a
mistake).

Otherwise, check to see if websockify is installed somewhere (try
`which websockify`).  If it is, use that.  Otherwise, clone
websockify from github, and tell git to ignore that directory.

Packaged versions of noVNC should simply list websockify as a
requirement.  The debian packaging has been updated to reflect
this.

Closes #433

Support ExtendedDesktopSize and SetDesktopSize

* Added new tests for the setDesktopSize encoding
* Added new tests for the ExtendedDesktopSize encoding

* Added a resize request (setDesktopSize) triggered when connecting and by
  changes to the browser window's size.
* Hid the view-drag-hand when the display area is the same or smaller than the
  remote session size.
* Added a setting for the automatic resize feature.
* Updated vnc.html and vnc_auto.html to reflect the changes to the UI.

keysym.js needs inclusion in debian's install list

* Support sending the setDesktopSize encoding (client -> server)
* Support recieving the ExtendedDesktopSize encoding (server <- client)

* Split viewportChange into two functions, one for changing size and the other for changing position.
* Modified viewport code to be capable of changing to a bigger size in the context of a
  client-initiated resize.
* Made clearer distinctions between when viewport-clipping or not.
* Added public function for telling when viewport-clipping.
* Updated tests that were using viewportChange.

Unregister event listeners from websock.

Prevents possible memory and event notification leaks when tearing down
connection and reestablishing a new one.

Loads keysym.js

Without it, `XK_ISO_Level3_Shift` (at least) is undefined.

Bonus 3 bug fixes:
 * Meta is 0xFFE7 not 0xFE07
 * Super_L is 0xFFEB not 0xFFEC
 * Super_R is 0xFFEC not 0xFFED

The HEXTILE test which tested for a background tile followed
by an empty tile was only wide enough to actually test for one
tile, thus not actually testing the functionality.  It now actually
uses two tiles, thus actually testing the functionality.

Fix for typo from a recent pull

There is a minor typo in the recent pull  Simple fix.

Closes #412

Previously, if a HEXTILE tiles was received with a subencoding
of 0x00, it would draw a rectangle using data from the render
queue, which would result in random colored blocks when using
the HEXTILE encoding.  This is the result of a miscopy during
the refactoring.  It now has the correct functionality according
to the RFB protocol specification, which is to draw a rectangle
with the last set background color.

Closes #411

Previously, we were using the karma-sinon-chai package to
provide sinon-chai to karma.  This used an older version of
sinon-chai, and looks to be no longer maintained (it's been
a month since sinon-chai was updated).  A new package,
karma-sinon-chai-latest, is now used.  This package uses the
latest version of sinon-chai and sinon, just like karma-chai
uses the latest version of chai.

Commit 795fca23 changed the default
size from 640 to 240.  This broke a couple tests which depended on
the default size being 640.  Those tests have now been fixed.

Added in guidelines for contributing to noVNC

In CONTRIBUTING.md, you can now find a set of guidelines for
contributing to the noVNC project.  They detail coding style
information, requirements for pull requests, and how to run
the unit tests.

This fixes an issue where, when using true color, the changeCursor
function would not actually write the cursor to the target array.

Fixes #407

Fix subprotocols

Broken by b1dee947

The latest version of Node.js has a bug that
affects the Karma test runner.  A patch has been
merged to Karma, but has not landed in a version
yet.  Until a new version of Karma is released,
we should keep node at 0.11.13.

See karma-runner/karma#1182

(cherry picked from commit 9af2346a0cead634f3af5f390770ea65929c1f4a)

Make Utils.js use Object.define to modify Array

Previously, we were modifying Array's prototype using
simple assignment.  This can mess with enumeration/iteration.
Thus, we now use Object.defineProperty with enumerable set to
false.

See #366