This commit introduces a new package `pkg/fips`
that bundles functionality to handle and configure
cryptographic protocols in case of FIPS 140.
If it is compiled with `--tags=fips` it assumes
that a FIPS 140-2 cryptographic module is used
to implement all FIPS compliant cryptographic
primitives - like AES, SHA-256, ...
In "FIPS mode" it excludes all non-FIPS compliant
cryptographic primitives from the protocol parameters.
