Material design modifications

Updated dialogs to use Appcompat material design.
Changed color schemes. Colors from here: http://www.materialpalette.com/light-blue/blue-grey
Update the category spinner to look better, also it uses a dialog now.

Replaced the repo update ProgressDialog with custom AlertDialog. (No ProgressDialog in AppCompat because it's not recommended by Material Design guidelines).

If I'm doing anything wrong, I'll be glad to correct it.

Screenshots: