Adds Resque::Config#initialize

* Explicitly pass a Redis-like to config.redis in Resque#redis= instead of doing so implicitly, making it easier to test
* Move Redis::Backend::connect tests from config_test.rb to backend_test.rb
* Move/add Resque#redis= docs to Redis::Backend::connect

Props to @yaauie for pairing with me and writing most of this
Rearrange config attr_accessor :redis
Remove trailing whitespace
Merge pull request #1055 from edward/refactor-config-and-resque-singleton

Adds Resque::Config#initialize
add yarddoc to lib/resque.rb
Merge pull request #1062 from engineyard/nonoko

remove un-used Capybara dependency
Merge pull request #1057 from yaauie/yarddoc-resque

add yarddoc to lib/resque.rb
Merge pull request #1059 from engineyard/raise_exceptions

Don't swallow exceptions (and fix a test too)
Merge pull request #1061 from engineyard/flaky_tests_2

"fix" flaky blpop tests
add yarddoc to lib/resque/worker.rb
Merge pull request #1063 from yaauie/yarddoc-resque-worker

add yarddoc to lib/resque/worker.rb