Replace rake functions with python paver functions
Deprecated rake functions issue a warning and then call paver
replacements

Bring Paver commands up to date with master for servers, assets, and docs.
Revert deprecation of quality, tests, and i18n for a future pull request.
Deprecate workspace migration
Merge pull request #2520 from edx/will/paver-rebase-part-1

Paver (Part 1)