Linting js files

Hi,
as in the comment this PR contains a linted collection of files.
Short recap:
+ as reported in the commit message there's a ```runImmediately()``` method that isn't defined in the file where it's used (I see that the definition is in the ```peerconnection.js```);
+ there was in ```mediastream.js``` line 65 a reference to a ```_pending``` variable but the variable name was ```pending```. I thought that it was a typo.

Imho there's the need of a little refactor to expose the ```runImmediately()```.
As usual open for review.