Bug 824783 - [email] "No mail in this Folder" overlaps the actual emails in the sent folder if the phone times out. regression fix, a=bustage-fix

land regression fix:
https://github.com/mozilla-b2g/gaia-email-libs-and-more/pull/111
Merge pull request #7404 from asutherland/email-cangrowsync-regression

Bug 824783 - [email] "No mail in this Folder" overlaps the actual emails...
Auto-merge from branch 'master'