add user.add and user.list methods

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added user.remove method

This commit was sponsored by The Hoodie Firm
with support from NLnet: http://nlnet.nl
http://go.hood.ie/thehoodiefirm
rework user api and add user.get method

This commit was sponsored by The Hoodie Firm
with support from NLnet: http://nlnet.nl
http://go.hood.ie/thehoodiefirm
Merge branch 'master' of github.com:hoodiehq/hoodie-plugin-api