Whether or not a class needs to run as a service is an implementation decision.

Please note that this commit only uses the @Test annotation
where exceptions are thrown at the end of the test,
because otherwise the test would not be executed completely.

Examples for this are in DatabaseComponentImplTest where many exceptions
are thrown in close succession or in ConnectionRegistryImplTest where an
exception is thrown in the middle of the test.

Addresses comments for !48.

Use BLAKE2s to generate tags.
KDF arguments for key rotation.
Frame IV format.

SHA-256 is still used for password-based key derivation (will be replaced with Argon2) and Fortuna.

Implementation is based on the BLAKE2b implementation from BouncyCastle, and is
therefore licensed under the BouncyCastle license (which will make future
upstreaming of the code easier).

Test vectors taken from NaCl paper.