Updating wiki to remove old tars, jars, etc.

This is a squashed version of the previous website to make it faster (hopefully) to clone phoenix.
Updated language reference to indicate that LIMIT executes before ORDER BY
Update mislabeled performance chart
Add sqlline screenshot
Update gh-pages/README.MD to refer to Master branch
update language reference with 1.2 features
Merge branch 'gh-pages' of github.com:forcedotcom/phoenix into gh-pages
Add new perf. images
Update perf. image
Update salted perf. image
More perf. images