Add Training Library resource type.

[birchamp]

gA needs to be able to create repos for the new Training Library resource (ex: en_tl) so users can have the repo and manifest set up before translating in tCC. You can look at the manifest in https://git.door43.org/unfoldingword/en_tl as an example.

Since this repo is not book specific it should be treated like the Translation Words repo.