openbsd_pkg: add upgrade argument.

Running the module with the argument "upgrade=yes" invokes an upgrade of
all installed packages.

While here clean up some comments.

Functionality requested by @qbit.
Refactor openbsd package upgrade change to work more like yum/apt
Simplify logic by using required=True.
openbsd_pkg: revert "changed" simplification.

module.exit_json() does not like when the "changed" variable contains a
match object:

TypeError: <_sre.SRE_Match object at 0x81e2ae58> is not JSON serializable
zabbix_maintenance: set state to be present by default

Signed-off-by: René Moser <mail@renemoser.net>
mysql_replication should not connect to the 'mysql' database

All the actions by the mysql_replication plugin can be done by connecting to the NULL database. There is no need to connect to the 'mysql' db, since there are permissions problems when connecting to remote hosts, e.g. when you want to query "SHOW MASTER STATUS" on a remote host.
mkfs.xfs uses -f instead of -F flag

mkfs.xfs uses the -f instead of -F flag to force creating a filesystem on a devices that have an existing filesystem
Merge pull request #3 from eest/openbsd_pkg-upgrade

openbsd_pkg: upgrade all packages when name is '*'
Merge pull request #4 from resmo/feature/zabbix_maintenance-default-state

zabbix_maintenance: set state to be present by default
Merge pull request #16 from kustodian/mysql_replication_no_mysql_db

mysql_replication should not connect to the 'mysql' database
Merge pull request #18 from jravetch/devel

mkfs.xfs uses -f instead of -F flag