Add decorator option for language links

Callback function to be called when a language link is prepared
Can be used for custom decoration.
Arguments:
(a) the $language - the language link jQuery object
(b) languageCode

The function can do any styling, changing properites etc on the passed link.
See examples/decorator.html for example usage.

Change-Id: I5a67654440a07cf7dfac683e22dcb5000ded0bfe
Minor formatting changes

Change-Id: I3ffd7029165ff614c13000b333ed30d3874fba28
Merge pull request #159 from santhoshtr/decorator

Add decorator option for language links