Enhance REST API

[fcollonval]

The current REST API could be improved by at least passing the git repository folder in the url like for example the content notebook API. In particular this will allow to use the full spectra of HTTP verbs in a more RESTful spirit.

For example here are some interfaces from the notebook content API:

HTTP verb	URL	Action
GET	/api/contents/path/file	Return a model for a file or directory.
PUT	/api/contents/path/file	Saves the file in the location specified by name and path.
PATCH	/api/contents/path/file	PATCH renames a notebook without re-uploading content.
POST	/api/contents/path/file	Create a new file or directory in the specified path.
DELETE	/api/contents/path/file	delete a file in the given path

Idea of evolution

Before	After	Note
POST /git/add	POST /git/path/add
POST /git/add_all_untracked		Should be merged with add using arguments to distinguish
POST /git/add_all_untracked		Should be merged with add using arguments
POST /git/all_history	GET /git/path/all_history	Should we keep it?
POST /git/branch	GET /git/path/branches
POST /git/changed_files		Unused ?
POST /git/checkout	?	They are 3 behaviors within this endpoint. Probably need to be distinguished
_	GET /git/path/branches/branch	Branch switch
_	POST /git/path/branches/branch	Branch creation
_	?	Discard all changes
POST /git/clone	POST /git/path
POST /git/commit	POST /git/path/commits
POST /git/config	GET /git/path/config	Split get and set config actions
_	POST /git/path/config
POST /git/delete_commit	DELETE /git/path/commits/hash
POST /git/detailed_log	GET /git/path/commits/hash
POST /git/diff	GET /git/path/diff
POST /git/diffcontent	?	Can it be merged with the previous one?
POST /git/init	POST /git/path	To be merged with clone
POST /git/log	GET /git/path/log	History count as query argument
POST /git/pull	POST /git/path/pull	Need to stay POST for authentication
POST /git/push	POST /git/path/push
POST /git/reset	?
POST /git/reset_to_commit	?
GET /git/server_root	GET /git/server_root
POST /git/showprefix	GET /git/path/showprefix
POST /git/showtoplevel	GET /git/path/showtoplevel
POST /git/status	GET /git/path/status
POST /git/upstream	GET /git/path/upstream

[kgryte]

@fcollonval Agreed. Would be nice to make the APIs more restful.

Somewhat related, but will mention here, I had worked on a separate server extension for "simplified" Git actions before a decision was made to contribute here. IMO, we do need to do some refactoring of the current server extension anyway, so maybe we can do both, both clean and refactor the routes, at the same time.