Bug 849525 Clean up mailnews/subscribe.{js|xul}. Part 1:  fix whitespace issues r=Mnyromyr rs=Mnyromyr.
Bug 849525 Clean up mailnews/subscribe.{js|xul} Port some improvements from Thunderbird r=Mnyromyr moa=Mnyromyr.
Also: Comment only fixes (punctuation, capitalization) and remove some useless dump() statments.

TB patches ported:
Bug 360510 - Make subsription checkboxes accessible
Bug 441705 SetUpServerMenu is no longer used
Bug 455947 Fix subscribe ui to select the server of the selected folder
Bug 624092 - Use of undefined object SubscribeOnLoad()