add checkstyle plugin and config file
add new blank line rules to checkstyle settings
Merge branch 'develop' into issue/670-refresh-code-style
new script to check introduced style errors
Merge branch 'develop' into issue/670-refresh-code-style

Conflicts:
	build.gradle
	src/org/wordpress/android/util/StatsRestHelper.java
Remove Tasks, and ThreadPoolExecutor. Just enqueue the network calls in Volley, and let it play with them.
Use a ThreadPoolExecutor to parse network responses and update the UI
Use a task to handle network errors
Remove unused tasks
fix #1227
fix #1221
fix #1222
fix #1223
fix #1224
fix #1225
Update comments
Fix an issue where country views doesn't correctly show today/yesterday.
Merge pull request #1217 from wordpress-mobile/feature/1199-Remove-ThreadPoolExecutor-Stats

Stats - Remove ThreadPoolExecutor and use Volley threading capabilities
Merge pull request #1228 from wordpress-mobile/issue/1227-misc-npe

fix #1227 and other NPEs
fix #1231: null check WordPress.currentPost