Use Int16Array instead of Object array for LUTs and uses positive indexes.

This results in 4x speedup of the storedPixelDataToCanvasImageData and
probably 12x speedups for storedColorPixelDataToCanvasImageData.
GenerateLut should also be much faster.
*) updateImage() now takes invalidated as a parameter
*) added example of how to dynamically generate images
Update backlog.md
Update backlog.md
Merge remote-tracking branch 'upstream/master'
Merge pull request #4 from jpambrun/int16InsteadOfObjectArray

Use Int16Array instead of Object array for LUTs and uses positive indexes.
Added support for trigger an event when an image is loaded
Updated the event handling example to show how this works
- Thanks to @jmhmd for this idea
Updated code contributors list
Made first letter of CornerstoneImageLoaded uppercase for consistency
Added some notes on the performance optimization related to signed data
Changed eventData parameter for CornerstoneImageLoaded so it is consistent with the other events
Updated readme with guidance on code submissions and maturity of the project
oops fixed markdown formatting of last submit
Add method to get pixel array with modality LUT transformation applied

Conflicts:
	dist/cornerstone.css
	dist/cornerstone.js
	dist/cornerstone.min.css
	dist/cornerstone.min.js
Merge pull request #7 from jmhmd/upstream

Add method to get pixel array with modality LUT transformation applied
Bumped bower version, updated contributors list
Merge remote-tracking branch 'upstream/master'
Reject imagePromise before purging and make re-implement purgecache.

Rejecting imagepromise before the are discarded fixes issue #5. The
then() function is never called and the cacheSizeInBytes is not set into
an incoherent state.

purgecache was modified for clarity.
Added dist and build to gitignore.