Added generate_name() function in Organism class

Fills 'identity' key in organism's status dictionary a randomly generated 32-character string.
Updated dose.py to set 'identity' and 'deme' keys in each individual's status dictionary

Expected results are not shown in final report. There is no variation among organism 'identities'.
Changed population_report() function to report organism 'identities' instead of genome sequences
Changed population_report() function to report organism 'identities' instead of genome sequences
Merge pull request #15 from clarencecastillo/master

Updated dose to include 'identity' and 'deme' in every organism's status dictionary