PyGrid integration

[vvmnnnkv]

This PR adds following changes:

• websocket, http support added in GridAPIClient (selected depending on provided pygrid URL)
• authenticate, cycle-request, get-model, get-plan, report are doing actual pygrid requests
• model diff is actually serialized to protobuf and sent to pygrid (report request)

It was tested with following notebooks:
OpenMined/PySyft#3185
And this PyGrid branch: OpenMined/PyGrid-deprecated---see-PySyft-#509

[codecov]

Codecov Report

Merging #109 into master will decrease coverage by 6.76%.
The diff coverage is 30.76%.

@@            Coverage Diff             @@
##           master     #109      +/-   ##
==========================================
- Coverage   77.86%   71.10%   -6.77%     
==========================================
  Files          21       21              
  Lines         610      713     +103     
  Branches       81       93      +12     
==========================================
+ Hits          475      507      +32     
- Misses        118      183      +65     
- Partials       17       23       +6     

Impacted Files	Coverage Δ
src/job.js	0.00% <0.00%> (ø)
src/syft_model.js	0.00% <0.00%> (ø)
src/grid-api-client.js	9.63% <10.66%> (-0.89%)	⬇️
src/types/plan.js	91.66% <80.00%> (+0.75%)	⬆️
src/protobuf/index.js	94.73% <92.30%> (-1.27%)	⬇️
src/types/message.js	83.33% <100.00%> (ø)
src/types/placeholder.js	100.00% <100.00%> (ø)
src/types/torch.js	93.54% <100.00%> (+2.63%)	⬆️

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