Added Plot Function + Small Fixes

[aliasgherman]

No code has been changed from algorithm perspective

Plot code is added as v01 with minimal options. We return the matplotlib plot in the results['plot']

Readme has been improved a bit.

Certain errors like gaps in datetime would cause assertions due to middle samples not being sufficient from num_obs, some errors on the data types (like int64 throwing error), were fixed.

Test cases were improved for compatibility (assertEquals -> assertEqual) etc.

I am now using this code for my daily office work without problems. I am open to test with other datasets if needed too.

Also, most of the assert are not out as Codacy does not like them (they may be compiled out of the code)