chore(build): upgrade to gradle build tools 0.9
Merge pull request #22 from passy/gradle-upgrade

chore(build): upgrade to gradle build tools 0.9
chore(deps): upgrade test dependencies
Merge pull request #23 from passy/dep-upgrade

chore(deps): upgrade test dependencies
fix(library): check dir before writing outState

Check whether mSelectedDir was set before saving the directory in
onSaveInstanceState in case that the fragment is detached very quickly.

Fix #20