Make it simpler to run the tests.

Fix the limitation where tests can only be run if the current directory
where the codingstandards are checked out is called 'CakePHP'. Instead
any directory that can also be used in a classname will work.

The eval bits are hacky has hell but avoid even more strange practices
like storing each sniff twice or having totally crazy file layout to
facilitate tests.
Update travis config file.
Remove 5.2 from travis.

It does not support autoloader pre-pending which makes the test
class workarounds impossible.
Merge pull request #35 from cakephp/test-simplify

Make it simpler to run the tests.