Bug 857376 - Use 2k page_size for databases on B2G. r=mak, sr=mossop, a=tef+

--HG--
rename : storage/test/unit/test_page_size_is_32k.js => storage/test/unit/test_page_size_is_2k.js
Bug 860171 - Re-add SendRingIndicator. r=gyeh, a=tef+
Bug 858833 - During an update, downloadAvailable is sometimes not reset to false after an error when it should. r=fabrice, a=lsblakk