Update README and Changelog

[jronak]

Update README and changelog with gRPC streaming and other details.

Changelog

• Add support for gRPC streaming requests and responses for both single and benchmark RPC calls.
  • Multiple requests can be passed from the CLI option -request, optionally delimited by space or comma -request='{"request": "1"} {"request": "2"}'
  • Requests can be interactively passed from the STDIN by setting CLI option -request='-', this is useful with bi-directional streaming to interactively send and receive stream messages
  • Delay between each consecutive stream request can be ensured by setting CLI option -stream-interval='5s', this ensures there is at least a gap of 5 seconds between requests
• Add grpc-max-response-size option to accept large responses for gRPC calls.

[codecov[bot]]

Codecov Report

Merging #330 (994fddf) into dev (b68c9de) will decrease coverage by 0.18%. The diff coverage is n/a.

@@            Coverage Diff             @@
##              dev     #330      +/-   ##
==========================================
- Coverage   90.49%   90.30%   -0.19%     
==========================================
  Files          54       54              
  Lines        2671     2671              
==========================================
- Hits         2417     2412       -5     
- Misses        179      182       +3     
- Partials       75       77       +2     

Impacted Files	Coverage Δ
handler.go	80.89% <0.00%> (-2.81%)	:arrow_down:

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[Dogild]

I am seeing some documentation updates along the release(https://github.com/yarpc/yab/pull/330/commits/cbc36c744329f37f74b972782097597dfaf09c9f), can we do this in another PR? It is extremely painful to review this here since we do not know what was really added or not.