Optimize Prism queries

Uses eager loading for Prism visualization to avoid N+1 queries
Add a Note to Teachers

Add text to explicitly state the experimental nature of the website
Notice update

Added praxis team
Merge branch 'master' into develop
Fix typo
Wayne fixed it by moving the caching the word_markings.
Merge branch 'master' of github.com:scholarslab/prism
Adds community forum with fake google pic.
Real prism community.
Upgrade ruby.
Upgrades .ruby-version.
updates the travis.yml file.
Removes rvm testing from travis.yml.
Add foreman to development group
Merge branch 'develop' of github.com:scholarslab/prism into develop
Merge branch 'master' into develop