project_search_results.rb

Gitlab::SearchResults and Gitlab::ProjectSearchResults are libraries we
are going to use to get search results based on query, enitity type and
pagination.

It will allow us to get only issues from project #23 where title or
description includes 'foo'.

Ex:

search_results = Gitlab::ProjectSearchResults.new(project.id, 'foo', 'issues')

search_results.objects => # [<Issues #23>, <Issues #34>]
search_results.issues_count => 2
search_results.total_count => 12 (it includes results from comments and
merge requests too)

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>