Due to a overly-stringent regex, the project template API was 404'ing
when C++ was requested as the template. Loosen the regex to allow `+`
and `%` for URL-encoded characters.
Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/57857
Updates specs to use new rails5 format.
The old format:
`get :show, { some: params }, { some: headers }`
The new format:
`get :show, params: { some: params }, headers: { some: headers }`