Modified message composition screen to enable capture button

Implemented the capture button in the message composition fragment. The
message composition fragment is the new home of the capture button and
the type selection buttons.

Modified ImageMessageFragment and image_message_fragment.xml to remove
the capture button and type selection button. Extracted original on
click calls to functions, that can be accessed by the message
composition fragment.

Only taking a picture (on click) or a video (on long click) are
currently working. I need to add in the ability to switch fragment types
as well.