Issue loading file with colon in directory name

I ran into an issue when trying to load a file with a ':' in the directory name:

```
'Orion/O:IR Images/Orion_A_J_3x3.fits'
```

when this happens, it looks like ``SharedGlueSession.add_data`` gets called with ``file_path`` set to:

```
IR Images/Orion_A_H_3x3.fits
```
