Added reporter class, refactored any output methods to reporter.
Implemented public find_reference() method to IzVerifier.
Dependency paths only displayed for undefined conditions in dep search, not
variables.
Added option of failing dep tests on undefined vars.
Added small section on contributing to README.
Added a few basic test cases for finding references using IzVerifier.
Fixed a bug with izpaths keeping collections statically.
Fixed some bugs with dependency test searching for 'quoted' literal condition
ids it found in source code and reporting them as missing from conditions.xml.