Merge pull request #73 from gwicke/refactor-parsoid

Refactor parsoid
Use bluebird as the global Promise implementation
Return a 404 for getLatestFormat of a missing page
Merge pull request #74 from wikimedia/no-latest-rev

Return a 404 for getLatestFormat of a missing page
Merge pull request #75 from gwicke/bluebird

Use bluebird as the global Promise implementation
Bump preq version
Merge remote-tracking branch 'wikimedia/master'