fix(upgrade): Added upgrade to deactivate TinyMCE and activate CKEditor.

Fixes #6653.
Merge pull request #6657 from brettp/tinymce_to_ck

fix(upgrade): Added upgrade to deactivate TinyMCE and activate CKEditor.
docs(about): Add contributing, history, releases, and values docs
Merge pull request #6687 from ewinslow/docs-about

docs(about): Add contributing, history, releases, and values docs
fix(docs): Fixed links in mediawiki format instead of reST. Removed reference to Transifex
Merge pull request #6689 from Srokap/docs

fix(docs): Fixed links in mediawiki format instead of reST. Removed refe...
docs(security): Add security rst docs
Merge pull request #6688 from ewinslow/docs-security

docs(security): Add security rst docs
docs(i18n): Add minimal i18n documentation ported from wiki
docs(rewrite): Finish migration from what we had in GDocs
Merge pull request #6692 from ewinslow/docs-i18n

docs(i18n): Add minimal i18n documentation ported from wiki
Merge pull request #6691 from ewinslow/docs-index

docs(rewrite): Finish migration from what we had in GDocs
docs(themes): converts theming docs to rst
Merge pull request #6693 from ewinslow/docs-themes

docs(themes): converts theming docs to rst
Merge github.com:Elgg/Elgg