quest api setup/teardown

[robnagler]

• setup and teardown of quests is important, especially when there's shared state.
• allow setup to change the arguments passed to the apis. The example is slicops which wants context to be passed in, since the field_value is implicit
• quest api needs api_name saved on self (qcall)
• setup/teardown can change api_name
• should it be possible to have apis that are prefixed by a module name, e.g. from slicops screen.camera. This might make it harder to search for. The flat name space has advantages, but that means api's need prefixes for their module name. Perhaps api_module could be passed to allow disambiguating. http server would need to fixed to support/require this when there are collisions.