Check for commented lines?

As discussed on IRC, augeasproviders doesn't check for comments in lines and you said checking for comments is nice feature request. Ok, here we go :D

Example:
lldpd in debian configured with shellvar. By default file content is:
```shell
# Uncomment to start SNMP subagent and enable CDP, SONMP and EDP protocol
#DAEMON_ARGS="-x -c -s -e"
```

Ok, let's go with config:
```puppet
class lldp::config {
    shellvar { 'enable_lldpd':
        ensure   => present,
        target   => '/etc/default/lldpd',
        variable => 'DAEMON_ARGS',
        value    => '-x -c -s -e',
        require  => [
                    Class['lldp::install'],
                    Class['snmp::deploy']
                    ],
        notify  => Service['lldpd']
    }
}
```
Result:
```shell
# Uncomment to start SNMP subagent and enable CDP, SONMP and EDP protocol
#DAEMON_ARGS="-x -c -s -e"
DAEMON_ARGS="-x -c -s -e"
```