Modified a single line in parse_classic_otu_table to allow it to correct...

...ly parse classic tab delimited OTU tables that do not have a leading comment line (fixes issue #678). Added a specific test for this case in test_parse_classic_otu_table. Ran all_tests.py to make sure it didn't break anything down stream and it appears not to have. The specific case I am resolving with this commit is where you sumbit a classic OTU table instead of a summarized OTU table to make_3d_plots.py as the biplot otu table (the -t option).