Changes to binary scripts.

Added PCoA and PCoA_bubble binary scripts.
Added example plots for PCoA script.
Updated PCoA.txt for documentation
Changes to qiime-tools documentation

Added the example PCoA bubble plot with citation for ISME article.
Updated binary scripts

Modified iTol and prune_otus scripts for uniformity in documentation.
Merge pull request #2 from akshayparopkari/master

Updated PCoA and PCoA bubble documentations