new icon, new "want to use this?" dialog // FREEBIE

* new DialogFragment that looks great on >ICS, and good enough on gingerbread
* new icon with high-density assets (required a bump to build-tools 19 for xxxhdpi folder support)
* fixed bug which hung up RedPhone if you "cancelled" the dialog by tapping outside of it without answering positive/negative
updated gitignore for mac shit