Use package name as custom resolver process name

The process name was being assigned null. This meant that after the
process attached we weren't matching the name in
ActivityStackSupervisor.attachApplicationLocked(). That meant missing
the call to realStartActivityLocked() and then the resolver didn't
start until window manager timed out and resumeTopActivity was
called five seconds later.

Fixes bug 18301267.

Change-Id: If3721caeebb309c6054150b2f707e3d6e38a74d2