Grégoire Pineau 97c56347a1 Better error reporting when a config key in template is Unknown
This patch will allow to fix the following bug much faster:

```
1 error(s) occurred:

* Unknown configuration key: output_directory
```

Related configuration:

```
"output_directory ": "build/sl_base/",
```

After the patch, the error reporting will be:

```
1 error(s) occurred:

* Unknown configuration key: "output_directory¤"
```
2015-03-05 10:23:21 +01:00
..
2014-05-06 18:52:02 -07:00