Restore ability to filter tests on command line
Restore ability to filter tests on command line

ember-cli/ember-cli@ad86fa1 made it possible to include ?hidepassed
in the testem configuration, but broke the ability to pass a filter
to ember-cli-mocha via the command line. Without this change,
the filter fails because the URL contains `??`.

HeroicEric/ember-cli-mocha,switchfly/ember-cli-mocha,zenefits/ember-cli-mocha,zenefits/ember-cli-mocha,trentmwillis/ember-cli-mocha,lazybensch/ember-cli-mocha,HeroicEric/ember-cli-mocha,switchfly/ember-cli-mocha,ember-cli/ember-cli-mocha,trentmwillis/ember-cli-mocha,cowboyd/ember-cli-mocha,ember-cli/ember-cli-mocha,lazybensch/ember-cli-mocha,cowboyd/ember-cli-mocha,blimmer/ember-cli-mocha,blimmer/ember-cli-mocha