Changed __version__: 1.6.0-dev to 1.7.0
Changed __status__: "Development" to "Release"
Updated doc/conf.py version
Updated version strings in docs.
Fixed some RST script errors.
Fixed otu_cat_sig.py output desc to avoid errors
Merge pull request #964 from jrrideout/170-version-change

Version updates for 1.7.0.