Added GoogleCalendarManagerTest into taskbuddy.googlecal package

The original GoogleCalendarManagerTest file was inside the file package.

Why is this change necessary?
- To standardise the JUnit test programs with the main programs

How does it address the issue?
- By standardising
Removed the origina GoogleCalendarManagerTest file.

The new file is in the googlecal package.
GoogleCalendarManager add API updated

Why is this change necessary?
- To fulfil the requirements of Database

How does it address the issue?
- Database no longer requires the returning of the Google Calendar Event
  ID (GID). Only requires a boolean value to indicate if the event was
  successfully added to Google Calendar servers.

What side effects does this change have?
- There is a need to add the GID into the task object from
  GoogleCalendarManager. This has not been implemented yet.
Updated way of authorizing Google Calendar token

Why is this change necessary?
- Previously, GoogleCalendarManager could not recover if the key had
  expired.

How does it address the issue?
- By developing an algorithm that checks allows GoogleCalendarManager to
  check whether the key is valid. If the key is valid,
  GoogleCalendarManager uses the existing key to create a Calendar
  object. If the key is invalid, GoogleCalendarManager will generate a
  new key.

What side effects does this change have?
- When the user is offline, GoogleCalendarManager thinks that the key is
  invalid, and prompts the user to generate a new key, even if the key may
  actually still be valid.
Added functionality for Google Calendar Manager to check online status

Why is this change necessary?
- Previously, when the user is offline, GoogleCalendarManager thinks that
  the authorization key is invalid, and prompts the user to generate a new
  key,   even if the key may actually still be valid.

How does it address the issue?
-  GoogleCalendarManager now calls the method "isUserOnline" to check for
   online status of the user. This method pings google's servers to
   determine connectivity with Google. If the ping fails, a false boolean
   variable is returned to the database.
Added JUnit test case for isUserOnline() method

This test case ensures the isUserOnline() method in GoogleCalendarManager
works as expected.
New stub methods to obtain task attributes for adding into Google Calendar

Why is this change necessary?
- Stub methods will allow for easier implementation of reading of Task
  objects from database

What side effects does this change have?
- GoogleCalendarManager is now able to successfully add tasks into Google
  Calendar, and to return the Google Calendar Event ID back to the caller
  of the add method.

      a7637ea
Merge branch 'master' of https://github.com/cs2103aug2014-f11-3j/main