Remove unused import
Add docs content
Add aiohttp docs to intersphinx mapping
Set intersphinx against Python 3 docs
Better hierarchy formatting
Ensure client to read all the data

The issue raises when FlowControlChunksQueue is used: on .read() it
returns the first batch of bytes it receives from transport not all
excepted, so this may cause issues with JSON decoding etc. which relays
on the same call.
Implement GET|PUT|DELETE|COPY /{db}/{docid} API calls
Allow override request and response classes on request
Add special HttpStreamResponse to handle multipart responses
Implement basic multipart reader