Users can break Gliffy macro by moving the diagram image file

To Reproduce

1. Create a page called gliffy images
2. Create a Gliffy Diagram on a page called gliffy diagram
3. on gliffy diagram page​ click the paperclip icon to see attachments
4. locate the gliffy png file and click properties
5. ​enter "gliffy images" in the page field and Save

Environment:
mjensen.jira-dev.com
Gliffy 6.5.2
5.8 SNAPSHOT

Result:
the .png disappears and the page now shows a macro error

Environment
dpabst.jira-dev.com
Gliffy 6.3.2
5.7-OD-47-038

Result:
the .png moves to the designated page and is previewable. The gliffy diagram is still on the original page and may be edited. However, when the Gliffy editor opens the controls and shapes are all missing.