Export calendar bookings as .ics (iCal) file

Import/Export the entire calendar as .ics would be good to have as well.

Committed on:
Portal 6.2.x GIT ID: 8a62a55332210a686b8541683ac0fe37dbfefa21.

PASSED Manual Testing using the following steps:

1. Create an Event
2. In the Enterprise Portlet, click on the drop down menu next to "My Calendars" and click on Manage Calendars.
3. Click on Action > Export for Joe Bloggs and save the ics file
4. In Google Calendar, click on the drop down menu next to "My calendars" and click on Settings
5. Click on Import calendar (next to the Create new calendar button) and select the exported ics file.
6. In the Google Calendar, assert the event that was created in the Enterprise Calendar was imported correcly
7. In Google Calendar, create a new calendar and add a new event.
8. Click on the drop down menu next to "My calendars" and click on Settings
9. Click on Export calendars (next to the Create new calendar button) and save the file
10. In the Enterprise Portlet, click on the drop down menu next to "My Calendars" and click on Manage Calendars.
11. Click on Action > Import for Joe Bloggs and select the ics file exported from Google Calendar
12. Navigate back to the Calendar view and assert the event displays
13. Assert that events in different time zones are correctly exported/imported

Fixed on:
Tomcat 7.0 + MySQL 5. Portal 6.2.x GIT ID: 6d280617f28523c41bd9dae101c9b948eb6abaf0.
Plugins: e7ae77e77906fbce53cc21107f893b31f93f6b21.

After exporting the ics file from the Enterprise Calendar and importing the ics file to Google Calendar, the user will be able to see that all the events display correctly. Creating events through Google Calendar, and then exporting it to an ics file and importing it into the Enterprise Calendar also seems to be working correctly.