Exec command free with a safety locale

Systems configured in other languages/locales return another text different than Swap.

Also, please, consider modify the rest of invocations written this way:
```
- export LC_LANG=C && unset LANG && <CMD>
```
to this other way:
```
+ LC_ALL=C <CMD>
```
in order to modify the locale at command scope instead of at shell scope.
Merge pull request #21 from dgilm/patch-1

Exec command free with a safety locale