Post model cleanup:

 * Removed all database work from the Post model.
 * Added new WordPressDB method to return a post with a localTablePostId.
 * Corrected variable naming in post model (camelCase) and their getters/setters.
 * Removed old migrateDrafts method from WordPressDB.
Merge branch 'develop' into issue/968-load-post-fixes

Conflicts:
	src/org/wordpress/android/ui/posts/PostsActivity.java
Added some basic Post tests, fixed up tests that used old method of loading/creating Posts.
Fixes test from not running. props @maxme
Moved some mime type methods to MediaUtils, and moved MediaUtils class to the 'util' folder.
Before uploading media, get the correct mime type and file name. Fixes #1081.
Get the file extension through the mimeType instead of the file path. Fixes issue where huge file path would be displayed for queued media items.
 * Removed save, update and delete methods from Post model, instead call the db methods when performing CRUD operations.

 * Fixed some null checks to use TextUtils.isEmpty.
Cleaned up the getMediaFile method.
Fixed EditPostTest.
Merge branch 'develop' into issue/968-load-post-fixes

Conflicts:
	src/org/wordpress/android/ui/posts/PostsActivity.java
	src/org/wordpress/android/ui/posts/PostsListFragment.java
Moved file extension code out to its own method so that it can be used in MediaGridAdapter easily.
Merge branch 'develop' into issue/1081-photos-app-media-library

Conflicts:
	src/org/wordpress/android/ui/media/MediaBrowserActivity.java
	src/org/wordpress/android/ui/media/MediaGridAdapter.java
	src/org/wordpress/android/ui/media/MediaItemFragment.java
	src/org/wordpress/android/util/MediaUtils.java
Removing an unneeded toUpperCase()
Adding missing 'more text' when loading a post from the DB
Repositioning more text load to make more contextual sense.
Checked for Post model String getters that were still checking for null. Some of the checks I didn't replace with TextUtils.isEmpty() because a user may have wanted to empty out a field, such as post excerpt or keywords.
Added notNullStr wrapper to getQuickPostType to be consistent with other string getters in the Post model.
Removing an extra line.
Merge pull request #1082 from wordpress-mobile/issue/1081-photos-app-media-library

Fix for broken media uploads