Begin work on GUI component
Modify parser to communicate with GUI, update AWTgui

Changes made
- Parser: Changed main method into userInput method
- Parser: Removed while loop
- AWTgui: Now able to accept user inputs in the Command box. Passes user
  inputs to parser when user hits enter / presses the SEND button
GUI in operation

Details
- GUI is now working for basic add, delete and display functions.
- GUI is able to display response for "invalid command"
- GUI is able to display the log file
Add ability to authenticate Google Calendar from GUI
Add break lines for display, modify window size
Add method to check calendar status from GUI
Merge branch 'master' of https://github.com/cs2103aug2014-f11-3j/main into wip/gui