GoogleCalendarManager successful connection to Google Cal

GoogleCalendarManager can now successfully connect to the Google Calendar
Servers. The add(Task) method (to be called by Database) is now able to
successfully add an event to the Google Calendar database.

Why is this change necessary?
-  This change is a significant step toward implementing reading the
   attributes from the Task object and adding the task as an event to
   Google Calendar

How does it address the issue?
-  Currently working on stubs to read values from Task object. Actual
   implementation to be developed soon.

What side effects does this change have?
-  Method to verify user's online status has been implemented
-  GoogleCalendarManager will use the previously stored authentication
   token to create Calendar objects, until the previously stored
   authetication code expires. A method has been implemented to make check
   for validity of the code. Once the code is invalid, Google Calendar
   Manager will assert the generation of a new code.
Merge branch 'wip/GCal'