Motivation: Creating duplicate resources currently results in a 500
error being displayed by the client, with no information about the true
nature of the failure.
Modifications:
* ResourceStore now converts any errors from the etcd client into
fission errors, capturing the reason for the error in the case of a
duplicate key (as ErrorNameExists)
* ErrorNameExists errors are signaled to the client with a
409 (Conflict) HTTP status
* MakeErrorFromHTTP() now reads the body of the error response to
retrieve the actual error message instead of using the HTTP status
message
* the controller client now uses MakeErrorFromHTTP() to centralize
status code -> error code mapping
* tests for all of the resources now check that duplicate resources are
reported properly
Result: The client can now provide more context when a duplicate name is
given
related to #112
Environments for functions. For now this is just the image URL for the
function run container. In the future, Environments will also have
build container image URLs, and perhaps parameters to those
containers.
Create/read/update/delete/list. Versioning will be added later. For
now, only the latest update is stored.
This implemenents create/read/update/delete/list for http triggers.
This isn't quite the final implementation: you can't look up old
versions by UUID since it only stores the latest update. I'll get to
that later.
