Add initial set of permissions tests
Backup and restore device state between subsuite invocations.
fixup! Backup and restore device state between subsuite invocations.

Only save device state once per run.
Merge pull request #79 from dminor/bug-1006025-fix

Add initial set of permissions tests
Merge pull request #80 from mozilla-b2g/jgraham/device_backup

Backup and restore device state between subsuite invocations.