add param converters
added checks for enabling param converters
configured ConvertExceptionListener
require zenstruck/controller-util:0.3+
use PSR-4, adjusted travis to push code coverage
fix invalid composer.json
remove hhvm tests on travis
added additional unit tests
added ParamConverter functional tests
added exception map functional tests
Merge pull request #1 from kbond/param-converter

Add param converters and exception map