Merge pull request #677 from tbruyelle/646_PropagateThreadExceptions

Propagate exceptions on @Background/@UIThread annotated methods
Merge pull request #678 from tbruyelle/674_WarningOnNullRootContext

Log a warning when a @RootContext field isn't populated
Fix IntentBuilder startForResult

In a fragment, startActivityForResult must be called from the fragment and
not from getActivity(), or the fragment's onActivityResult will never be
hit.

Now IntentBuilder may have up to 3 constructors, depending to the
classpath content.

According to the constructor chosen, startActivityForResult will
be called on Activity, android.app.Fragment or
android.support.v4.app.Fragment.

From the AA user perspective, this fix is quite transparent, he just
have to call Activity_.intent(this), whatever he's in a Fragment or an
Activity, it will work.