add main unit tests
Add validation for step and the validateOnlyToAdvance attribute
Unit tests for validation
Merge branch 'master' of github.com:mgonto/angular-wizard

Conflicts:
	dist/angular-wizard.js
	dist/angular-wizard.min.js
	src/step.js
	src/wizard.js
refactory for validation
undo steps when go to a previous step and attribute validate-only-to-advance renamed to validate-always
Merge branch 'master' of github.com:mgonto/angular-wizard

Conflicts:
	dist/angular-wizard.js
	dist/angular-wizard.min.js
	karma.conf.js
	src/wizard.js
add some tests for basic functionality
Merge pull request #25 from cristianspinetta/master

Add validations for the step transitions