Rename paranoid function to removeNonAlphanumerics

`removeNonAlphanumerics` more properly describes what the function is doing.  Also updated the tests.

Cons:
* It will break any cakephp applications using paranoid
* It will remove humor from the cakephp repository.

Pros:
* It will help dispel the myth that php developers are professionals without standards.
* It will be properly named.