HUE-1741 [dbquery] bugs

- PostgreSQL now requires a database name.
  This means that get_databases will return the configured database.
- Moved rdbms libs + db selction part into rdbms app.
- Errors now go away when a new query or explain is ran.
- Revamped front end storage management.
HUE-1501 [oozie] Support coordinator datasets from non HDFS
HUE-1601 [oozie] Workflow editor shouldn't display deleted action in Import Action

Filter out workflows from Spark app
Fix race condition when installing all examples for the first time