Update dependencies

* Remove non-dev dependency on the codesniffer package
* Add dependency on PHP >= 5.3.3
Update README to match my GitHub rename
Simplify test infrastructure

* Remove run-tests test runner
* Assume composer's autoloader is present, do not attempt to fall back
  to include_path
Simplify travis-ci configuration

* Remove php_codesniffer composer require hack
* Have phpunit run the test suite directly
Remove problematic "negative-value" and redundant tests

ICU seems to have changed the default formatting for negative numbers in the
en-US locale, and since that really isn't testing any feature of Money, we can
remove those tests without loss of coverage. We can also remove the de-DE test
which was not improving coverage above what was already there.