Working on #5. Started implementing a command handler.

This commit added a very basic straightfoward command handler.
When submit is clicked, the input command is dispatched to
commandHandler (which resides in command.js). The commandHandler
function will replace space with underscore and assert hasOwnProperty
in lower case.

This is also related to #1, for the user story (comment 2)
Fixed #6. Added gmail.js to data/library/gmail as submodule.
Fixed #7. Added jQuery to data/library/jquery.
Working on #8. Trying to get rid of GLOBALS undefined error.