Merge pull request #8 from pradhanta/master

Submit interaction
Merge pull request #9 from pradhanta/master

Added variable utility class
Merge pull request #10 from pradhanta/master

Added code to ensure no negative long values are generated. Update query fired to the backend to be different for question and challenge.
Merge pull request #11 from pradhanta/master

Added code to fix issues discussed in email and added start over interaction.
Merge pull request #12 from pradhanta/master

Fixed issue pointed in the email, changed visitor id to string. Added a simple done interaction.
Merge pull request #13 from pradhanta/master

Removed Unused class files (Token and TokenValidator.java)
added sentence parsing logic
Fixed issue with session clearing. Selected item is set to null