Validators::isEmail and Validators::isUrl now recognizes one letter TLD

In current implementation, "example.l" is not a valid URL for Validators -- which is problematic when developing on local machine with custom domains in hosts file.

According to RFC, Domain Names can have TLD one letter long, so ".l" should be accepted by Validator.

Link to RFC with grammar for Domain Names: http://tools.ietf.org/html/rfc883#page-56