mixer: dump database fixes

* Adds new command `inveniomanage database dump` to allow dumping the
  content of the database using the mixer.

* Fixes imports and trailing white spaces on json dump.

Signed-off-by: Esteban J. G. Gabancho <esteban.gabancho@gmail.com>
search: tuning of hierarchical facet

Tested-by: Tibor Simko <tibor.simko@cern.ch>
Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>
search: quickfix pagination troubles with facets

* Fixes problem with ignoring pagination options while using facets.
  (closes #2306) (PR #2308)

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>