Log Message:
Updated docsis to 0.9.1.

changes since 0.9.0:

- add support for ModemCapabilities
- add support for Subscriber Management Filter groups
- make SNMP VarBind encoding more "compatible" with other encoders
- cleanup argument handling, fix bug with error printing
- fix bug where SnmpMibObject OID output would switch to numeric format
  after a decode_oid
- re-organized and beautified source code