These commits resolves #240 and resolves #241

#241
- Instead of using external library to extract metadata of video, recording video and setting metadata of video is done by Aikuma internally.
- bitsPerSample is meaningless in AAC audio codec in video. So it is set as 0 currently.
- Video recording has 3 states: Record -> Stop -> Save

#242
- Now metadata input activity is divided into 4 activities: Review -> Recording name -> Speakers + languages -> Final confirm
- Metadata input by user is shown in the next activity
- In the final confirm activity, all information are shown including the recording as well.
- In case of recording-name and speakers+languages activities, OK-button is not enabled until at least one for each metadata is input by a user.
- Back-button in each activity helps a user go back to the previous activity.

etc
* DebugUtils is added for debugging use
* Interface MenuBeahviour.BackButtonBehaivour is added for additional processing when back-button is pressed
* Part of #280 (in Google-signout commit) and #245 (in mockup commit) is impelmented
* There is currently a crash of video-activity with Xperia phone.