add comprehensive unit tests

[anotherjoshsmith]

Any tests are better than no tests (which is where we are currently), but I'd like to get tests setup for each step of SGOOP to make sure any developments to the code don't break the package. This will have to wait a bit longer since I plan to refactor the code a bit, per the guiding design principles from the scientific python cookiecutter. When I am done, each piece of "scientific logic" should be tested separate from I/O operations.

Tests need to be implemented for (list subject to change upon refactoring):

• md_prob
• bin_max_cal
• mu_factor
• transmat
• eigeneval
• spectral

[anotherjoshsmith]

Yikes! Looks like I was a bit confused about the final structure of modules when I wrote this issue. I've added comprehensive testing of the scientific logic in analysis.py, merged to master in #8. Still need to write tests for sgoop.py