This pull-request resolves #279, #340, #352 and is related to #243, #283, #315, #320, #344, 

#243 
#315
1. When the auto-sync is checked in the setting, alarm is set to start Cloud-sync every 30 minutes and Boot-receiver is registered.
2. Boot-receiver will set the alarm again each time the device is re-booted.
3. Data-connection is checked inside the Cloud-Service. If it is not connected, the service will quit and restart after 30 minutes.
4. When the application starts, the sync-service will start regardless of 30 minute-scheduling

#279 : item_id is used in metadata

#283
1. Index file is created in the app-root path
2. Index file is used to show derivative recording files made by an user different from one who made a source.
3. It is indexed each time a derivative recording file is made.
4. TODO: Auto-creation of whole indexes for the case user deletes the index file by mistake

#320
1. Speaker-small-image.jpg, speaker-metadata.json are stored in each user's google-drive
2. This is indexed in fusiontable (metadata will be stored in fusiontable's metadata field)

#340 : archive-icon is changed

#344 
1. Because cloud-service will be restarted each 30 minutes, checking the cloud-storage is not a good approach for an objective of minimization of API calls.
2. Checking the cloud-storage will only happen when the app is firstly installed(when the app's private data is cleared) and when the user presses the cloud-sync button in the menu.
3. In other cases, the creation of new file(recording, speaker) is tracked in Aikuma and automatically logged to be uploaded later.

#352: Only one player can do a playback

PS
1. FileModel class is created and extended by Recording and Speaker
2. FileModel models the file-object from the viewpoint of GoogleCloud
3. All kinds of AIkuma files can now be uploaded to GoogleDrive and logged in FusionTable. (modelled by FileModel class)
4. Cloud-service's logic is totally changed for independent operation(regardless of application), efficiency, robustness and code-reusability
5. Support for multiple user-IDs 
   (multiple user's googleDrives / different user's states are stored in separate SharedPreferences)
6. Adding an user to the recording can be removed/added additionally multiple times