proper respond_to? check for default expiration change #19
tests and support for defining expiration parameter on worker basis or globally per ServerMiddleware #19
some documentation regarding expiration setting on Worker level  - fixes #19
proper description of setting expiration on worker basis. This also works in not Sidekiq:Status:Workers
Merge pull request #20 from RaVbaker/master

Tests for :expiration param settings and a new way of setting :expiration on Worker level
version bump to 0.4.0, readme and changelog updated
Update README.md

+Gem version badge
Rename Sidekiq::Status::Worker#num to Sidekiq::Status::Worker#at
Improve Sidekiq::Status::Worker#at interface
Add documentation about web interface