Bug 1264429: This patch creates the table, refactors the get_institution_config() method,
the Institution class, and the institution editing page, to use the new table.

Henceforth columns should only be added to the main "institution" table if they represent
a required setting (like name and displayname), or they need to be accessed frequently by
direct SQL queries.

Change-Id: I4564240d2c55ec2b6ec90868290a61cf4321460a