Guard2 api

```
    Hi, Guard here.

    You're including lib/guard/guard.rb ...

    ... which contains code deprecated over a year ago!


    This file will likely be removed in the next version, so make sure you're
    not requiring it anywhere to ensure safe gem upgrades.

    <snip>

    /Users/john/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/guard-2.8.2/lib/guard/guard.rb:45:in `<module:Guard>'
	 >> /Users/john/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/guard-2.8.2/lib/guard/guard.rb:3:in `<top (required)>'
	 >> /Users/john/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/guard-sidekiq-0.0.11/lib/guard/sidekiq.rb:2:in `require'
	 >> /Users/john/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/guard-sidekiq-0.0.11/lib/guard/sidekiq.rb:2:in `<top (required)>'
	 >> /Users/john/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/guard-sidekiq-0.0.11/lib/guard-sidekiq.rb:1:in `require'"

    Here's how to quickly upgrade/fix this (given you are a maintainer of the
    offending plugin or you want to prepare a pull request yourself):

      https://github.com/guard/guard/wiki/Upgrading-to-Guard-2.0#changes-in-guardguard

    Have fun!
```