- added optional gss_opts to sasl_prefs
- response for challenge only return response. securelayer wrapper
  is returned by receive("success",...) call.
- added support for include for SASL::Buffering (it was only extend before)
- changed io.read/write to sysread/write in SecureLayer
- updated to rspec 2.0
- added securelayer tests
- added support for algorithm=md5
- added support for auth-int (integrity)
- support for auth-conf (confidentiality) for
  ciphers rc4, rc4-40, rc4-56, des, 3des
- a secure_layer wrapper is returned for receive("success",...)
- updated to rspec 2.0
- added securelayer tests for digest-md5 (only integrity for now)
- added vim backup file to gitignore