Implement websockets!

[GrandMoff100]

Closes #189

[GrandMoff100]

Trying to copy https://github.com/home-assistant/home-assistant-js-websocket

[codecov]

Codecov Report

Attention: Patch coverage is 92.74194% with 27 lines in your changes missing coverage. Please review.

Project coverage is 97.71%. Comparing base (6884520) to head (78b5385).
Report is 49 commits behind head on dev.

Files with missing lines	Patch %	Lines
homeassistant_api/websocket.py	82.29%	17 Missing ⚠️
homeassistant_api/rawwebsocket.py	92.72%	8 Missing ⚠️
homeassistant_api/models/domains.py	92.85%	1 Missing ⚠️
homeassistant_api/rawclient.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #196      +/-   ##
==========================================
- Coverage   99.59%   97.71%   -1.88%     
==========================================
  Files          20       25       +5     
  Lines         990     1315     +325     
==========================================
+ Hits          986     1285     +299     
- Misses          4       30      +26     

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