add support for fr-ch

added support for switzerland french.
there is an issue though
they use `'` as thousands delimiter. it's ok with formatting numbers but when i try to unformat string i get `NaN`
this is obviously due to regex that leaves `'` in initial string https://github.com/adamwdraper/Numeral-js/blob/master/numeral.js#L109
```javascript
string.replace(/[^0-9\.'-]+/g, '')
```
and hence `Number('1\'000')` returns `NaN`
not sure what is that for,  so i just left it as it was