Load the imfile module in a separate conf file

The ```LoadMod imfile``` line, within the ```imfile.erb``` template is responsible for loading the imfile module.
However, if multiple configuration files are generated from the same template, the application throws the following warning:

```
2014-07-15T17:02:32.927594+00:00 simon-test rsyslogd-2221: module 'imfile' already in this config, cannot be added [try http://www.rsyslog.com/e/2221 ] 
```

In order to fix this, ```LoadMod imfile``` has been removed from ```imfile.erb``` and added into a separate template ```load_imfile.erb```. This generates a unique configuration file whenever the ```rsyslog::imfile``` define is called.

The '01-' suffix within the file name ensures that rsyslog loads the *imfile module* before reading the *imfile* configuration files.

The behaviour of the module is unchanged.