This request resolves #43, resolves #122, resolves #216, resolves #258.

#43
- Gesture(Pressing the green-arrow button) should be >= 0.1sec to be valid
- At the start or After one respeaking-segment is recorded, invalid gesture(<0.1sec) makes the original play at the start or the end of last respeaking-segment.
- After valid-gesture and before respeaking-record button is pressed, invalid gesture makes the original play at the end of last original-segment(played by the last valid-gesture)
- This is done by player.playOriginal() in ThumbRespeakingActivity

#122
- Feedback are added
- Download/Upload status (eg. Upload: [uploaded file count] / [total count of files to be uploaded] [Current uploading file name] )
- FTP server setup error status (eg. There is no writable directory on the server)
- Lastest sync-success date (eg. Last success sync: [date])
- ServerCredential is modified to store latest sync-success date
- These feedbacks are printed by SyncUtil.updateSyncTextView()

# 216
- rewindAmount is set in SettingActivity and stored in SharedPreference(Default value: 1sec)
- This value is passed to PhoneRespeaker/ThumbRespeaker
- ThumbRespeaking: After each respeaking-segment is recorded, original rewinds back for rewindAmount and plays again
- PhoneRespeaking: If the respeaker becomes silent, original rewinds back and plays again.
- SimplePlayer is modified to support rewind(msec)

#258
- TL-WR1043ND: FTP server should be set up at 192.168.0.1
- FTP server setup: give write-permission for specific folders
- Aikuma tries to find writable folder and uploads all items to the folder found first