Modifed validate_demultiplex_fasta.py to address issues in issue #975
Merge branch 'validate_demultiplex_fasta_dup_ids_list' of github.com:/walterst/qiime into validate_demultiplex_fasta_dup_ids_list
Modified code to address comments
Merge pull request #1213 from walterst/validate_demultiplex_fasta_dup_ids_list

Modifed validate_demultiplex_fasta.py to address issues in issue #975