Fixe gem build error ERROR: (Gem::InvalidSpecificationException)

Duplicate dependency on rspec (>= 2.0.0, development), (>= 2.0.0)
Make sure sidekiq is required
Fix for RSpec 3 Support
More Rspec 3 Fixes
Updates CHANGES.md for 1.1.0 release
Updates CHANGES.md for 1.1.0 release
Update Changes.md
Merge branch 'pr/44'

Conflicts:
	CHANGES.md
Merge pull request #42 from ifeelgoods/topic_fixe_gemspec

Fixe gem build error ERROR: (Gem::InvalidSpecificationException)
Adds credit to mourad-ifeelgoods for pull request #42
Merge pull request #43 from ifeelgoods/topic_fixe_require

Make sure sidekiq is required
Adds credit to mourad-ifeelgoods for pull request #43
Emphasise project description in README
Merge https://github.com/philostler/rspec-sidekiq
Require rspec/core