Update README.md

add README source code highlight
Merge pull request #3 from mibamur/patch-1

Highlight the source code snippets in README
Remove sublime metadata files from repository
Increase karma capture timeout
Improve webcam test with a video element check.

It also validates the attributes set on the element.
Add jshint rule to ignore undefined in test file
Fix bug of not setting the class in the placeholder element

Also added tests to make sure it is now working.
Fix mistake on README for error callback
[#4] Improved specs to cover almost all code branches,
except the canplay event in the video element