Solves issue #758 -- a truly monumental commit

this addresses issue #758

wanted to make sure the tutorial was exactly correct so I searched for the first time that 'filter_otus_from_otu_table.py' was mentioned in the revision history. 

found 98a64044258cfeda2d89b7f6de955e8a998feb9f as the revision that added filter_otus_from_otu_table.py. there was an earlier commit (week time difference) where the filter_otus_from_otu_table.py did not yet exist, but the version of qiime was still considered 1.4.0-dev (that commit is 1ec285922eb00251a86591eba73dbe43749f4392). 

this means that the instructions on http://qiime.org/tutorials/open_reference_illumina_processing.html are wrong if someone has a 1.4 version checked out between Dec 14th and Dec 21st 2011. this is probably not a big issue.