Rename paranoid function to removeNonAlphanumerics

Per discussion in https://github.com/cakephp/cakephp/pull/1498/files , pointing to the new branch.

`removeNonAlphanumerics` more properly describes what the function is doing.  Also updated the tests.

Cons:
* 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.
* Still backwards compatabile

Tagging previous code reviewers:
@ravage84
@dereuromark