Implement present / exists checking. Context changing not implemented
Add more specs.
Add tests for 'checks presence of property'
Refactor tests for context changing.
Split out tests more.
Finish off prop tests for prop.
Add context changing documentation
Revise readme order.
Update index.html
Revise doc building and content.
Add prop context doc
More comments about context changes.
Refine language
More param docs
Add returns doc strings
Update history notes.
More to do's.
Readme rewriting
Tighter whitespace
Merge pull request #9 from FormidableLabs/feature-properties

Feature: Add properties to some assertions.