Added a SourceTracker tutorial rst file and image related to that tutorial
Merge branch 'master' of github.com:qiime/qiime into sourcetracker_tutorial
Removed example output from help command in order to avoid confilicts with changes to the option list in future releases.
added text to clarify the description of the filter_otus_from_otu_table.py
Improved the description of adding columns to the mapping file.
made a few minor changes to clarify descriptions and fix grammer.
added the print_qiime_config.py command to the tutorial.
Adds library and script files for make_bipartite_network

This functionality is being built to replace make_otu_network.py because that script has become nearly non-functional given changes to Cytoscape and Qiime including the biom format.
Updated script and added library rewrites as well as tests.
Added test data and outputs.

Verified that it works with %prog command in help documentation.
Addressed comments by @lkursell and @ElDeveloper
Addressed changes suggested by @ElDeveloper and @josenavas
Significant changes to script interface

Changes mades to the script interface so that the --md_fields option would be required. This, coupled with a change to the library, allows an individual to passbiom files which have jagged metadata (if metadata is list or string). Laura pointed out that this was likely the most common use case, and so it needed to be supported.
Merge branch 'sourcetracker_tutorial' of git://github.com/johnchase/qiime into st-tutorial
renamed tutorial to be less method-specific in case we have other source tracking methods in the future
added mechanism for qiime to know about sourcetracker
changed mechanism by which QIIME knows about SoruceTracker
started on some edits to the @johnchase's tutorial
Added a space in doc string to resolve positional argument failure.
Modified so resolve jenkins failures

added script_usage_output_to_remove directories to the script.