Initial backgrounding JNI support.
https://github.com/openpeer/opandroid/issues/528
Merge branch 'feature-20140818-jni-backgrounding' into feature-20140820-backgrounding
#533 add jni wrappers for backgrounding
Merge branch '20140401-dev-stable' into feature-20140820-backgrounding
#534 backgrounding app change
#538 add device shutdown/reboot listener to shutdown stack
javadoc update
#541 core logger now working
 #541 fix wrong log preference title
reformat CallFragment and optimize for debugging
 #544 optimize getUserByPeerUri and callFragment for debugging