new functions and sub-modules in phenoscore module

[abearab]

• update README format and content
• minor bug fixes
• draft a new sub-module in phenoscore called evaluate
  • related to Gold standard AUC/ROC hit comparison across pipelines #4
  • includes functions for calculating ROC-AUC and Precision-Recall AUC scores.
  • courtesy Tyler Fair (@tdfair) and M. Horlbeck, (@mhorlbeck)
• get best best transcript as lowest p-value for each target
  • close enable extracting genetable_collapsed by leveraging guides targeting multiple transcripts of same gene #85
  • close collapse the gene-transcript indices into a single score for a gene by best p-value #90