Updated README.md to refect actual code necessary to get states

Code listing for Inspection did not reflect the code necessary to produce the output that was indicated.

job.aasm.states produces an array of AASM::State objects, which need mapping to produce the symbols necessary.
Merge pull request #115 from danlo/master

Updated README.md to refect actual code necessary to get states
use the short mapping
better Travis CI icon
reformatted travis yaml configuration
use latest Rails versions (for Travis testing)
Add [sequel](http://sequel.jeremyevans.net/) support.

I am trying to migrate some activerecord code to sequel, and this makes
aasm work for sequel out of the box. This is not yet feature complete
as for activerecord, missing some scope related features. However this
could be a start, and to be honest, since we're not using them, this is
far good enough for us.

I have tried my best to make this aligned with activerecord and mongoid,
and I've overridden `aasm_read_state` for sequel, because there's no
`new_record?` but only `new?` in sequel, and there's no `blank?`,
either. (which I believe is provided in activesupport, which sequel
does not depend on, and I don't want to force people to depend on that.)

Thanks for considering.
use class method instead of instance method in scope example
fix Travis build for Ruby 2.1
Merge pull request #120 from moserrya/master

use class method instead of instance method in scope example
fix scope controller example in the README
Add a section for Sequel support.
Merge pull request #119 from godfat/sequel

Add sequel support.
running tests with Sequel, too
more links in the README for Sequel
added entry for Sequel to the changelog
mongoid is not yet compatible with Rails >= 4
updated Rails versions
Merge branch 'master' into aasm4