in-app image media preview

// FREEBIE
refactor ListenableFutureTask and make saves async

// FREEBIE
replace ABS with AppCompat

// FREEBIE
enable proguard

// FREEBIE
shorten blocks of text

// FREEBIE
padding workaround for bug in appcompat-v7 21.0.0

bug: https://code.google.com/p/android/issues/detail?id=77982

// FREEBIE
clear pending slides when attachment reselected

Fixes #2012

// FREEBIE
Beginning of libtextsecure refactor.

1) Break out appropriate components.

2) Switch the incoming pipeline from SendReceiveService to
   the JobManager.
Move API around.
Transition the outbound pipeline to JobManager jobs.
Move API around a little, eliminate TransportDetails interface.
Add account management interface to libtextsecure api
Add support for dependency injection, and accompanying tests.
Fix some bugs with PKWM padding and attachment detection.
Let's have JobManager only deal with checked exceptions.

Also, switch to Builder for JobManager construction.
Rename library to libtextsecure
Modernize libtextsecure layout
Refactor out old classes.
Move dependency up to parent.
Move DirectoryUtil up to parent.