show/services: don't navigate to the right

When using list/services for show/services (services for a single host)
we us an ugly PREG-based hack fixing the base link target. This got
broken by the multiselect feature, now it's working again. We need a
better solution for this.
ShowController: don't show a random service

When you chose a host and clicked on "Services" the GUI used to show
a random (the first) service. Made no sense, should work as expected
right now.
css/tabs: waste less space for dropdown

Dropdown arrow is smaller right now and is slightly rounded like the
other tabs are.
js/ui: remove hardcoded/duplicated with/height
js/events: do temporarily not respect tab focus

This has been added for keyboard navigation but caused some trouble.
Postponed for now.
js/events: improve search field change detection

This used to be nasty since "search" is the field with the initial
focus. Right now we detect "real" changes, this might be implemented
in a more generic way for all autocompleting fields later on.