Miscellaneous contact-detail fixes.

View-pager containing contact details and social updates are now
scrolled by the appropriate amount when ContactDetailTabCarousel is
swiped.  Also, fix "bounce-back" where the carousel improperly
selected the wrong tab (i.e. the one you just swiped away from).
Finally, make it possible to start a swipe back to the "about" tab
from the "updates" tab (previously, you had to initiate the swipe
on the partially-revealed "about" tab).

In ContactDetailFragment, only make photos tappable when either:
- the photo is settable (i.e. the contact is not read-only), or
- the photo should expand when tapped.

Bug: 6009463

Change-Id: I291e0c42b1d77a11babc7a9cb282a19cdb305025