add method String#replace_All

which will do a replace of all instances (vs just the first one, which is the default of the native js **replace** method)

with it, this 

``` coffee
@.req.params.file.to_Safe_String().replace(/_/g,'/')
```

would become

``` coffee
@.req.params.file.to_Safe_String().replace_All('_','/')
```
