WebSearch: stemming and '*'

* When a trailing '*' is used in a search over an index for which
  stemming is enabled, removes first the trailing '*', applies
  stemming and readds the trailing '*'.
  (closes #2468)

Signed-off-by: Samuele Kaplun <samuele.kaplun@cern.ch>
Merge branch 'sam/2468-websearch-stemming-star'

* WebSearch: stemming and '*'

Signed-off-by: Samuele Kaplun <samuele.kaplun@cern.ch>