Fix browser problem rebased

This is a partial fix for Issue #128

The problem is that new Browser will throw an exception when it can't find a proper browser. When this happens it interupts the rest of the preferences configuration and eclipse-color-theme is not functional in this state. 

This fix handles the case where the browser cannot load and allows the rest of the preferences dialog to construct minus the preview pane.

I also add the bundles to the manifest that were already used by the project to create the preferences dialog (swt and ui.forms).