fix(sa-learn): amavis can't do bayes check if not mask 777

Service amavis even though part of group vmail who has mark 770
on '/var/spool/spamassassin', can't write lockfile to do a bayes
check.

Set '/var/spool/spamassassin' mask to be `777` with owner
`debian-spamd:vmail` recursive. so that amavis bayes check works.

MR !9

include/docker-entrypoint.sh

@@ -35,6 +35,8 @@ mkdir -p /var/lock/fetchmail
 
 chown debian-spamd:vmail -R /var/spool/spamassassin
 
+chmod 777 /var/spool/spamassassin
+
 if [ "$1" == "setup" ]; then