Merge pull request #928 from strzalek/specify_capybara_ver

Use capybara 2.0.x
Use mock redis.

This will help out with mocking Redis for our new tests, and
makes our tests a teeny bit faster.

Fixes #886
Typo, but unnecessary anyway.
Merge pull request #930 from rtlechow/patch-1

Typo, but unnecessary anyway.
Add #jruby? to Kernel
Do not register QUIT & USR1 signal handler when on jruby