LPS-37724 Export/Import of portlets in a dialog

Jorge, this makes the portlet refresh when closing the dialog instead of when starting the import process.

I have some concerns though:
- You won't be able to test it until we fix a javascript issue with the refresh (I sent an email to @natecavanaugh about it)
- The portal level portlets in the control panel don't seem to work fine with this. (You can test Roles, Site Templates, Sites... etc)