UI: Select dataType for search indices
Init backend processing of search index dataTypes

TODO: make specific dataType in makeKey() operation
Merge remote-tracking branch 'remotes/kylef/pr-indextypesnewmaster' into demo
Fix a warning
Get dendrite to compile again, fix passing key types from UI to backend
work around a bug where firefox tries to submit an empty file on load
Pass upload errors back to the user.