Do not generate new dovecot cert if key or cert is already present
Do not generate new dovecot cert if key or cert is already present

(Bug #685896,#631257) Alexander Ufimtsev  <alexu@ucd.ie> and Jörg-Volker Peetz
<jvpeetz@web.de> independently provided the patch.

mswart/dovecot2deb,mswart/dovecot2deb,mswart/dovecot2deb,mswart/dovecot2deb,mswart/dovecot2deb