Update task model to include destination information

[shawnkoong]

Task Description The trip model needs to have a reference to the destination of the trip with details about this destination.

Mainly, the extra information needed are:

• [ ] destination name/address
• [ ] destination coordinate (will be used to locate within google map)
• [ ] destination viewport coordinates (will be used to set the coordinate bounds to show destination in the map)

Acceptance Criteria The above things should be included either directly or indirectly into the trip, as creating a new trip will include these information.

More information about what is provided by Google here

[shawnkoong]

Name/address will be a string All coordinates will be a pair of numbers that can be casted into doubles