Filterable list now sends request to filter the projects list
explicitly with `json` extension to avoid breakage when navigating back
from a project to the filtered project's list.
Reuse same search form and behavior for dashboard#projects, group#projects
and admin#projects. Repsect all other options like sorting, personal
filter when search projects by name. Create FilterableList JS class to
handle identical behaviour of projects and groups lists.
This change also makes filtering and sorting availabe on explore#projects
and explore#groups no matter if you are logged in or not.
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
