Bug 859573 - Part 1: Register script listeners via decorators; r=aki
Bug 859573 - Part 2: API for declaring virtualenv packages; r=aki

This patch provides a formal API for declaring virtualenv packages.
Before, scripts had to override create_virtualenv to install custom
packages. Now, they simply need to make a few API calls at setup time to
register packages and the default implementation of create_virtualenv
will do the right thing.
Bug 859573 - Part 3: Record system resource usage of scripts; r=aki
Backout e31f226cb264 for bustage
Bug 859573 - Use super() in DesktopUnittest.__init__; r=bustage
Bug 859573 - Part 3: Support optional Python package in virtualenv; r=aki
Bug 859573 - Part 4: Record system resource usage of scripts; r=aki
Bug 859573 - Trap ValueError encountered on B2G emu (vm) tests; r=bustage
Bug 859573 - Don't print original values when debugging exception; r=bustage

Printing the values confused the mozharness logging infrastructure and
threw an additional error.
bug 893574 - switch sendchange master. r=bustage
Backed out changeset f38888be196c (wrong patch for bug)
Merge Backout
Bug 887888 - Bug 829211 made Android Panda logs repeat every line twice. r=aki
bug 891114 - allow b2g sendchanges from try. r=callek
merge default -> production

--HG--
branch : production
bug 891114 - bustage fix
merge default -> production

--HG--
branch : production
Bug 892140 - Don't use sys.exit() in BaseScript.run(); r=aki
Added FIREFOX_23_0b5_RELEASE FIREFOX_23_0b5_BUILD1 tag(s) for changeset production. DONTBUILD CLOSED TREE a=release
Bug 892078 - Use cli.py instead of runtests.py when invoking gaiatests, r=aki