Basic parsing
Can now evaluate boolean logic and also parenthesised grouping
Evaluate parse tree
Just make the context a hash
Update README.md - with example, remove simplecov files

Also add gitignore file
Add Codeclimate and Travis Badges
Add travis configuration
Add Rake as a development dependency
Update gemspec file
We need the actual development dependencies
&& -> and; || -> or; context is an object, not a hash
Change hash to class in README.md example
Raise error when missing attribute is referenced
Order comparison operators to >= and <= work
Allow question mark in attribute
Bump version
Merge branch 'release/initial'