[api] Require running memcached.

Fixes: https://github.com/openSUSE/open-build-service/issues/454
[backend] update clients count in workerstatus
[backend] speed up code filtered _result query
[backend] do not get info of all packages for _repository buildinfo queries
[dist] fix name of cp437 kernel module, nls_cp437
[webui] port to possibly_empty_ul

This avoids duplicating conditions
[api] rename bs_user_id to user_id in all tables
[api] put the user login in the fixtures instead of the id

Same for roles
[dist] update spec file template to buildrequire procps
[webui] add test case that repository links
[webui] ignore empty arrays for main page statistics
[webui] fetch source files directly from backend
[webui] mls wants other icons for incidents
[webui] add a test case for /monitor events
[api] rename bs_group_id to group_id and bs_role_id to role_id
[api] map group_id to group in fixtures
[api] map more ids in fixtures
[api] fix for issue #469
[api] avoid confusion between our Event module and Clockwork::Event
[api] don't talk about killing, just kill

We may get a EPIPE for the puts, but we still need to kill