remove unnecessary class from navbar; fixes #757
Fix jruby builds. See travis-ci/travis-ci#1948
add #empty? to OpenStructWithHashAccess
No need to check for Turbolinks defined.

If there's no Turbolinks, we registered an event handler
for an event that will never be hired -- this should not harm
anything.

But the check introduces possible order-of-load errors, where
blacklight core accidentally ends up loaded before turbolinks,
so doesn't set up the event handler, but then turbolinks loads later,
so the event handler was needed, but didn't load. ran into this
with an engine that inserted it's 'require x.js' before turbolinks.
Best to avoid order-of-load dependencies if we can; we can.
ajax_modal: Combine trigger and preserve selectors

...in one event handler registration, so if something matches both
trigger and preserve selectors, it still only gets one event handler
call, not two. Fixes #772

Needs to be backported to a 5.0.2 release as a bugfix.
ajax_modal: ensure preserve selectors properly scoped.

since you can list multiple selectors, they each need to be manually listed as
scoped inside the dialog, just string-prefixing the ancestor wasn't going to
work.

Plus better comment docs.