Bug 838009 - fixes for change to 'sdcard' devicestorage. r=asuth

land https://github.com/mozilla-b2g/gaia-email-libs-and-more/pull/145
land https://github.com/mozilla-b2g/gaia-email-libs-and-more/pull/147
Merge pull request #8624 from asutherland/email-sdcard-lib-fix

Bug 838009 - fixes for change to 'sdcard' devicestorage. r=asuth