kerberos: Add initial kerberos support
First Kerberos implementation.
Increased the number of B64 tests.
Merge branch 'master' into kerberos
Merge branch 'master' into kerberos.
Some cleanup.
Reverting .gitignore and Makefile.ocaml to old state
Merge branch 'master' into kerberos

Conflicts:
	kerby/pkcs7.ml
Parse the pa_pk_as_req, only handle Diffie-Hellman case
Add parsing support for UDP messages
Hack etype to der_integer, because smallint overflows
Add support for hostaddress, fix enc_authorization_data
clientPublicValue is OPTIONAL
trusted_certifiers is OPTIONAL
Add support for ETYPE_INFO
Preliminary support for RSA authentication
Add more etype
Modularize kerb_pkcs7, and add support for EnveloppedData
Improve PADATA parsing and cosmetic changes
Finish AP_REQ support