Implement El Farol model

[rht]

This is based on projectmesa/mesa#1057, with changes:

• Updated to the new Mesa API
• Used Seaborn instead of Matplotlib
• Deduplicated code
• Added clarifying comments
• Removed the MultiGrid space because it is not needed in this model
• Added test

I confirmed that for the non-IBL version:

• the Add El Farol Problem in mesa framework under example folder mesa#1057 implementation is consistent with the NetLogo implementation in https://ccl.northwestern.edu/netlogo/models/ElFarol
• The result converges to attendance of 60
  
  

However, for the IBL version, the plot

does not reproduce figure 1 in Kumar 2016

Either:

• Drop the IBL version for now, redo it in a separate repo and separate folder
• merge this PR with the caveat in the README.md saying that the IBL version is still problematic

cc: @danielxu05

[rht]

I have decided to drop the IBL version for now, until I have figured out the bugs. This is a safer route, and that the PR becomes more compact as well.

[rht]

Removed the IBL code. This PR is ready.

[tpike3]

LGTM

*note for records --- IBL is Instance Based Learning