Fix code example in README to match description

[mattruzicka]

The description for the code example says:

You can validate against the normalized input as opposed to the raw input:

but the code example is still validating the raw input. This example "works" as long as the user enters a US number since the validation defaults to "US", but breaks if a an "IT" number is entered, for example.

Also, since we're validating the already normalized phone number, I don't think providing the "normalized_country_code" option is useful.

EDIT:
I added commit e44e76e because I'm guessing in the most common use case people don't want their records to be valid if the user enters a random string like "whatever", but also don't want to force a phone number - if they do, they should validate that the "phone_number" is present.

[coveralls]

Coverage remained the same at 99.809% when pulling ff0a589 on mattruzicka:master into 9e268a7 on joost:master.

[coveralls]

Coverage remained the same at 99.809% when pulling e44e76e on mattruzicka:master into 9e268a7 on joost:master.

[coveralls]

Coverage remained the same at 99.809% when pulling e44e76e on mattruzicka:master into 9e268a7 on joost:master.