Releases/Thunderbird 45.1b1/BuildNotes

Build 1

• (TB Drivers) Ship the l10n milestone
• (TB Drivers) Submit to Ship It
• Publish in Balrog
• Post-release tasks

Issues

• bug 1268310 Thunderbird 45.1b1 isn't starting
• multiple repacks failed and had to be retriggered
• gtk 3.0 libs are missing on our build machines so the update verify jobs failed 2/6 for linux64 and linux