CM71: Add option to choose in-call-style just like lockscreen style. Settings provider.

- Added on public user demand
- Adds an option under LockscreenStyle option
  probably the most userfriendly location for this!
- Finally replace those lockscreenstyl==1 lockscreenstyle==2 etc
  check in LockscreenStyleActivity.java with propper enums.
  That creeped me out for a while, since it was pretty dirty.
  The code now appeals much more to me

will resolve possible merge issues, when feature freeze is over

Change-Id: Id35be21ab505af7f75f0821ec00688d10d60e4bb