add support for more then one mech type
add support for more then one mech type

When using this with Win AD, I get the following OIDs i ticket
["1.2.840.48018.1.2.2" "1.2.840.113554.1.2.2" "1.3.6.1.4.1.311.2.2.30" "1.3.6.1.4.1.311.2.2.10"]
Only checking index [0] will result in error, while checking all works OK (krb5 found at index [1])
jcmturner/gokrb5