Merge pull request #17562 from crh0716/974253_v2

Bug 974253 - Set preferred network type on startup based on the user preference r=jaoo
Merge pull request #17519 from crdlc/bug-986047

Bug 986047 - [B2G][Dialer]Cannot select Add Comment when creating a new ...
Revert "Revert "Bug 986753 - [Tarako] Alarm Clock can get killed in the background and never ring." for suspicion of breaking gaia integration tests"

This reverts commit a968d8cd00fa1f370a2ea7e3994b5bb5391affd7.