add capability to create asset types via API
remove unnecessary comment
add test for AssetTypeApi
update endpoint for assettype as well
bump collins_client to include asset_type functionality
update collins_shell to support asset_type commands
update json matcher to support JsArray
add docs for collins-shell in AssetTypeApi actions
Merge pull request #191 from tumblr/gabe-arbitrary-assets

add capability to create asset types via API