use Rack::Utils.escape_html in Sidekiq::Web escape helper

  ERB::Util.h doesn't escape apostrophes and slash.

  Rack::Utils.escape_html is more performant and also escapes all char recommended by OWASP. (https://github.com/rack/rack/issues/27)
Sidekiq::Web escape display_args too
Sidekiq::Web escape args on workers and queues page
Sidekiq::Web add testcase for escaping
Merge pull request #1299 from lian/sidekiq_web_escape_args

Sidekiq::Web escape tests