Improve handling of configuration version control

[FreddieAkeroyd]

As a developer and user I would like only real changes to be pushed to git, currently there are many entries with no change recorded

Acceptance criteria:

• I add new or change existing configurations/synoptics and they appear in git
• I save a configurations/synoptic after making no changes and it does not appear in git
• files added/changed in settings outside on the blockserver are still picked up
• git url is http://control-svcs.isis.cclrc.ac.uk/git/?p=instconfigs/inst.git;a=summary