v0.2.7

Added:
- Adding FWHM plugin
- Adding STD to FWHM
- Adding CVDiagnostics, to check correlations in classifier inputs and
  other variables.
- Can define new features from existing columns
- More PDFs in ModelFactory, HypExp, ModExp, etc
- to_yaml and from_yaml utilities to deal with pandas dataframes
- Adding hashing function, ot hash generic python objects.
- JSON loader added to existing JSON dumper

Fixed:
- CV predict testing module had `_get_models` renamed to `ut.get_models`

Improved:
- Requiring latest version of TF
- Improve fitting parameter ranges
- Can set log or linear y scale for fit plots
- Can preparametrize peaky PDFs with scale and resolution