Add API documentation

[jdkent]

Add embedded documentation about the API so the endpoints are explained/understandable.

[PeerHerholz]

Currently there two python APIs available that, however, diverge in functionality and thus, as well as for housekeeping should be unified:

• pynv
• pyneurovault

The work on this issue should/will include the following tasks:

• list & evaluate functionality
• decide on API package & integrate the other one into it
• draft a first version of docs
• include a set of examples

Work will be performed using a new environment, created via conda create -n pynv_test and then installing the respective packages.

[PeerHerholz]

pynv

• installation via pypi works, results in 0.2
• creation of collection (api.create_collection) & adding of an image (api.add_image) works
• updating an existing image via api.update_image doesn't work (AttributeError: 'Client' object has no attribute 'update_image'
• deleting an existing image or collection via api.delete_image/.delete_collection doesn't work (AttributeError: 'Client' object has no attribute 'delete_collection')
• getting an existing collection via api.get_collection doesn't work (APIError: <h1>Server Error (500)</h1>)

[PeerHerholz]

pyneurovault

• installation via pip + github works, results in 0.1.3.
• dois_example.py works, thus obtaining all collections and wrangling the corresponding data
• download_example.py appears to work, thus downloading and filtering
• query_example.py doesn't work, some python 2/3 things and KeyError: 0 in images = get_images_with_collections(collection[0]["id"])[0]