Create tables from selected samples

This adds the ability to do a basic filter and merge on biom tables in order to get the required tables for an analysis. It also adds the ability to retrieve the filepaths of the biom tables created by datatype. 

This pull request also adds the creation of a mapping file for the analysis, as well as  retrieval of the filepath for it. 

The analysis handler has been tweaked to add the proper merged files to the jobs so they can be run on any selected samples.

Finally, this request tweaks the analysis_filepath table to add data_type as an option for biom tables in an analysis. 

I have tests in for the analysis object but my install of qiime is not working so someone else will have to test the full analysis workflow in qiita_pet. It should work, but let me know of any tweaks or issues needed during qiita testing. 

IMPORTANT: since biom is not working for python 3, the test WILL say they failed. If the tests pass for python 2.7, assume the code is good.