Save/load dashboard from/to influxdb works, #633
InfluxDB: save/load and search works, tag facets still to be done, but is not critical, #633
Merge branch 'influxdb_dashstore'
Changed search result model to be more datasource agnostic
Changed dashboard urls from /dashboard/elasticsearch/<title> to dashboard/db/<title>, old urls will still work
Updated changelog and config.sample.js with info about #633