[ELY-125] Add a DER encoder and decoder
Merge pull request #84 from fjuma/asn1

[ELY-125] Add a DER encoder and decoder
Delegating SASL client and server factories which establish an auth context for the duration of an authentication
SASL EXTERNAL client mechanism
SASL EXTERNAL server mechanism
Merge pull request #75 from dmlloyd/external

EXTERNAL SASL client and server mechanisms