Various updates (#70)

* Removed executable portion of beta_functions.py

This section was never used and very out of date. Removing it.

* modified:   notebooks/CSU_RadarTools_Demo.ipynb

* modified:   notebooks/CSU_RadarTools_Demo.ipynb

* Rename test file to the proper, expected name

* Drop EoL Python 3.4 from active test matrix and add current 3.7

* Minor refactoring that *should* streamline installing the test environment.

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Co-authored-by: C.A.M. Gerlach <[email protected]>