Support AES CTR stream cipher in FIPS mode

The stream cipher's state had to be changed from an Erlang tuple to a
NIF resource (an EVP_CIPHER_CTX structure) in FIPS mode. Because
OpenSSL 0.9.8 doesn't support copying this structure, the old state
was kept for non-FIPS enabled builds in order to provide a functional
interface.

The downside is that cipher states are no longer compatible between
FIPS and non-FIPS builds.
Do not advertise disabled protocols in FIPS mode
Fix disabling Blowfish ciphers in FIPS mode
Allow turning FIPS mode on and off

The recommended way would be to set the fips_mode application environment
parameter of the crypto application to true. This would turn FIPS mode on
when the NIF is loaded and would prevent loading the module on error.

An other method is provided via the crypto:enable_fips_mode/1 function, but
it is not recommended to be used in production, as it won't prevent the use
of the crypto module in case of an error, yet OpenSSL will disable all of its
crypto services. It is very useful for test suites however that need to check
both validated and not validated functionality.
Fix the AES CTR cipher in block mode
Remove digest calculation from NIF sign/verify code

This functionality is already implemented in the Erlang code.