Refactors the score loading and scripts functionality

This merge request:

• Move the biometric related functionality of bob.measure to bob.bio.base.
• Add confidence interval calculations
• Provide a score format for bob.measure with load functionalities
• Provide a generic plotting script bob measure in bob.measure using bob.measure input file format:
  • bob measure metrics: to compute thresholds and evaluate performances
  • bob measure roc: to plot ROC
  • bob measure det: to plot DET
  • bob measure hist: to plot histograms
  • bob measure epc : to plot EPC
  • bob measure evaluate: applies all the above commands at once
  • bob measure gen: to generate fake scores for bob.measure

Each command accepts one or several (dev,eval) score(s) file(s) for each system.