reorganize custom preindex workflows into a plugin structure

- couchapps
- mvp_apps
- (fluff in preindex-plugin branch of fluff repo)
log which plugins are being used during preindex
introduce changes to couchapps and mvp_apps to see if they preindex correctly

THIS IS TEMPORARY AND SHOULD NOT EVER GET MERGED
Merge branch 'daily_form' into autostaging
Merge branch 'vellum-includes' into autostaging
Merge branch 'multimedia-case-properties' into autostaging
Merge remote-tracking branch 'origin/sql-dailyformstats' into autostaging
Merge branch 'preindex-plugin' into autostaging
Merge branch 'testpreindex-dontmerge' into autostaging
update submodule refs