Fixed the case in the names of the json files for global settings and programme settings
Programme settings on save bug

Fixed the bug where programme settings weren't being saved because revisionable was only working for programmes
New migration for the 'empty_default_value' field in global_settings

Previously only added for programme settings
Tests for global setting and programme setting on save

This basically tests that the revisionable save mechanism works for global and programme settings as well as just programmes
Merge pull request #169 from unikent/bug/global-setting-save

Bug/global setting save