Draft of LTI documentation

First attempt at writing LTI documentation. Several questions for tech
reviewers.
Draft of LTI documentation

Another draft of LTI documentation, including a table of options
available in the Studio UI
Glossary revisions

Extensive revisions to glossary and minor changes to Appendix E and a
couple of other files (adding links)
Fixing conflicts

didn't see conflicts noted
LTI revisions

Revisions to LTI information based on feedback from Valera
fixing header

fixing header
Merge pull request #1943 from edx/markhoeber/documentation/glossary

Markhoeber/documentation/glossary