Add id field to institution table

[Nathan Lewis]

We are going to be adding some complex queries that require that institutions can be looked up by an integer id. We need an int for performance reasons and also the ability to store an "object id" which could contain institution ids, group ids, artefact ids, page ids etc, all in the same field.

As discussed with Aaron, the name field will continue to be the primary key and used in most places in Mahara. This patch doesn't utilise the field anywhere, it is preparation for future patches.

Version: master

[Mahara Bot (dev-mahara)]

Patch for "master" branch: https://reviews.mahara.org/3157

[Mahara Bot (dev-mahara)]

Reviewed: https://reviews.mahara.org/3157
Committed: http://gitorious.org/mahara/mahara/commit/dfdbdec32974f8816408a62e44c87d730f9f3b63
Submitter: Robert Lyon (<email address hidden>)
Branch: master

commit dfdbdec32974f8816408a62e44c87d730f9f3b63
Author: Nathan Lewis <email address hidden>
Date: Wed Apr 2 09:36:30 2014 +1300

Add id field to institution table (Bug #1300997)

- Preparing for future patches which require an integer id for performance and other reasons.
- 'name' will continue to be used as the primary key.

Change-Id: I5006b7f39edccc217fe5e4287585e62fc2545036
Signed-off-by: Nathan Lewis <email address hidden>