__package should use default parameters for --state

Otherwise the following "error" is triggered:

```
# manifest
      __package wget 
      __package wget --state present
```

```
# shell
$ cdist config -v localhost
INFO: cdist: version 2.3.7-75-gf165b56
INFO: localhost: Running global explorers
INFO: localhost: Running initial manifest /tmp/tmpuo6wqa/conf/manifest/init
ERROR: cdist: Object __package/wget already exists with conflicting parameters:
/tmp/tmpuo6wqa/conf/manifest/init: {}
/tmp/tmpuo6wqa/conf/manifest/init: {'state': 'present'}
ERROR: localhost: Command failed: /bin/sh -e /tmp/tmpuo6wqa/conf/manifest/init
INFO: cdist: Total processing time for 1 host(s): 0.604379415512085
ERROR: cdist: Failed to configure the following hosts: localhost
```

IMHO this should work. __package must be changed to use the default parameters and 'state' must be handled specially, different then the other parameters.