API should return 404 when the resource does not exist

[spesnova]

WHAT is this

Because of iruka is prototype, the API returns an error message like for now:

$ curl localhost:3000/api/v1-alpha/apps/hello
"No such app: hello"
$ curl localhost:3000/api/v1-alpha/apps/hello/containers
"No such app: hello"

But it should return 404 instead of the error message.

WHY this is problem

Returning the message causes following error when I'm using the CLI:

$ iruka apps
No apps to list
$ iruka ps --app hello
json: cannot unmarshal string into Go value of type []schema.Container

# same as `$ iruka ps --app hello`
$ curl -s -X GET localhost:3000/api/v1-alpha/apps/hello/containers
"No such app: hello"

HOW to solve it

I think I need to create registry errors.

1. registry returns error code and message if the resource does not exist
2. controller handle the error and returns 404 to client

[spesnova]

Config Vars

$ ./iruka config
# no output

# Server logs
[negroni] Started GET /api/v1-alpha/apps/hello/config_vars
100: Key not found (/iruka/config-vars) [271]
[negroni] Completed 200 OK in 2.071343ms