Adds default value instead of empty string into AccessTokenPreferences.
Replaces int with a constant in the OAuthRequester.
Replaces string literal in OAuthRequester with a constant.
removes string literals from TweetAdapter in favour of a string formatter to append the data retrieved from the twitter api call.
Edits the custom_shape.xml name to better represent its purpose; rounded edges. Removes redundant parent layouts from activity_list_view and authentication_activity.