Design docs sync & update

Design docs are now saved to git and designs.go handles comparing their content
to CouchDB and updating if necessary
Some tidying up before moving designs to own pkg
Change package name
Ignore VIM swap files
Code reorg, support for all design doc functions
Have Sync return list of changes
Improved change messages, handle missing docs
Handle all type of design doc functions

Added support for show, list, filter, and validation functions
Update LICENSE