LoginActivity changes:

- Removed test data and test buttons from login
- Changed all mentions of username to email as this was inconsistent
Added comments
DbManager and MyPostActivity:

- Added getAllUsersPosts method that returns all the posts of a certain
	user.
- Got rid of fake data in MyPostActivity

- MyPostActivity now displays the posts from the database.
added names to textViews where necessary 
changed a few strings to be more descriptive
EditPostActivity now has all fields filled when called from
MyPostActivity