- Wrote more unit tests to make sure filestore behaves as expected
- Renamed NewFileDataStore to DefaultFileDataStore, implemented a new
NewFileDataStore for unit tests.
- filestore now removes entire mailbox dir when last message is deleted
Use a global lock for reading/writing any index file. Possible
bottleneck, but good enough for now.
Don't create a mailbox directory until a message is being written to it.
Logging methods were renamed so they don't trigger go-vet warnings for
error() and Error() formatting.
Unit tests were updated to use new github.com/stretchr repo (was renamed
from stretchrcom)
Missing methods were added to Message mock object.
