Remove C:\fakepath\ from filename when importing property sets

Fixes #12184

### Turns this:
![prop_set_import_before](https://cloud.githubusercontent.com/assets/352182/5212820/e558358c-75bd-11e4-806e-b0a07d154cfb.jpg)

### Into this:
![prop_set_after](https://cloud.githubusercontent.com/assets/352182/5212857/c62dee58-75be-11e4-9e88-77ad16d09ec0.jpg)