Test commit.
A first draft of glossary terms
some formatting updates
Update glossary/index.md
Update glossary/index.md
some more links
More glossary edits
Some more glossary edits
Fixing some spelling mistakes

Added a definition for Operation and removed Supervised/Unsupervised Classification.
Merge pull request #1 from rcheetham/master

Drafting a new glossary for GeoTrellis docs