Minor change in auth response parsing

dovecot AUTH return message parsing changed.

Added configuration handling, no module code changes

Added autoconf handling of programs and libraries.
No changes have been done to module itself

Minor feature update and bugfixes

• Updated to include population of r->user field so other modules can see who is authenticated.
• Cleanup of sensitive data from used memory
• Enabled use of dovecot master user (impersonation) functionality