Do not call checkForLocalChanges when refreshing posts or page started by PTR
replace mIsRefreshing by isRefreshing()
move code in onRefreshStarted() to its own function for readibility
Merge branch 'develop' into issue/1092-double-refresh-of-posts

Conflicts:
	src/org/wordpress/android/ui/posts/PostsActivity.java
Merge pull request #1094 from wordpress-mobile/issue/1092-double-refresh-of-posts

Fix for double network calls on PTR