A user can type sync to sync his google storage

[newbishme]

We need to add in another command: CommandType.SYNC @yyhh91 Please update the logic to take in this signal @HaLinhh Please update InputParser to recognise this command

@yyhh91 After the above is done, the logic action to do is to call StorageHandler.sync();

[newbishme]

Sync function is implemented/fixed 10c1449 f38a44a 449a2d8; however it needs to be concurrent.