Add Correct HTTP Codes (In and Out)

Conflicts:

	application/controllers/api.php
Start Creating Table Of Index Update Times
Ensure We Have An ID To Increment On
Specify Model Table
Save Time Of Programmes Index To Table
Add Correct HTTP Response When Index Of Programmes Requested
Try and setup a less conservative caching policy
When in the API, we dont want to cache so turn caching off!
make sure api is at the start of the URI before disabling sessions
removing debug code and adding cache control header
stop the build breaking
Forget index data on simpleData save.
Use last_change cache to determine if data is out of date.
Add ability to set headers in tests
Add some tests
Add get_last_change_date_for_headers method to format headers as needed.
Use last update timestamp for index and subject_index
More tests
Remove API index table now we no longer need it.
Remove code references to APIIndexTime