Simplify/collapse attr and text asserts

	modified:   lib/selenium-cucumber/assertion_steps.rb
Fix bug in attribute asserts

	modified:   lib/selenium-cucumber/methods/assertion_methods.rb
Refactoring and collapsing asserts using regexes

	modified:   assertion_steps.rb
	modified:   methods/assertion_methods.rb
Changes to docs for changes in grammar
	modified:   doc/canned_steps.md