* Make the new fields RegistrationEnabled/LoginEnabled in types.RemoteSource
bool pointers (since they are new fields that don't exist in previously saved
remote sources) and default them to true if null when unmarshaling (or existing
remotesources will have registration and login disabled)
* Add options to cmd remotesource create/update to set the registration/login
disabled.
Just a raw replace of "github.com/pkg/errors".
Next steps will improve errors (like remote errors, api errors, not exist errors
etc...) to leverage its functionalities
* client: always parse the json error message field and return its contents
* Use ErrBadRequest and ErrNotFound in every handler and command
* Gateway: by default pass underlying service error (configstore, runservice) to
client keeping the status code and message. In future, if some errors must be
masked, we should change the specific parts that need special handling.
* Always return a json message also on error. For internal errors return a
generic "internal server error" message to not leak the real internal error to
clients
* Return 201 Created on resource creation
* Return 204 No Content on resource deletion and other action with no json
output
