Upgrade firmware to version 19 (improved timestamps from bug #2370), extra...

Upgrade firmware to version 19 (improved timestamps from bug #2370), extra protetions for buck boost Q7.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@3737 65c4cc65-6c06-0410-ace0-fbb531ad65f3