add is_public and owner attrs to image details dict

for openstack compatibility purposes, image details response json needs
to include the 'is_public' and 'owner' attributes. without these atts
set some client side consumers break. this PR adds those attrs to the
image details dict.
additional image attrs required by client side consumers
style - single quotes on min_disk
additional image property updates including min_ram
Merge pull request #70 from bodenr/bodenr/image-props

updates to image attributes
Adds .json suffix to each route

This fixes an issue where clients were expecting most (all?) routes to
be able to have a .json suffix.
Removes .json suffix from networks/subnets routes
Fixes test and removes some un-used imports
Merge pull request #74 from sudorandom/json-extention

Adds .json suffix to each route