Adding direct connect client

[kellrott]

Re-do of #131, but now the code is:

• Autogenerated using https://github.com/bmeg/protoc-gen-grcp-rest-direc
• Refactored for Arachne -> GRIP name change
• Also implements the editing API

[adamstruck]

I'd like to have a better idea of how this impacts performance before we merge this

[kellrott]

Using

time curl -d '{"query": [{"v": []}, {"limit": 1000000}]}' http://localhost/v1/graph/bmeg-test/query > /dev/null  

The original branch: 1m25.143s
New branch: 1m3.491s

As a note, the GRIP grpc based client does the same query in 0m41.103s

[adamstruck]

Please add HTTP auth test.