Properly handle missing authority checker

https://github.com/eclipse-equinox/p2/issues/235
diff --git a/plugins/org.eclipse.oomph.p2.core/src/org/eclipse/oomph/p2/core/P2Util.java b/plugins/org.eclipse.oomph.p2.core/src/org/eclipse/oomph/p2/core/P2Util.java
index 00a17a8..46be742 100644
--- a/plugins/org.eclipse.oomph.p2.core/src/org/eclipse/oomph/p2/core/P2Util.java
+++ b/plugins/org.eclipse.oomph.p2.core/src/org/eclipse/oomph/p2/core/P2Util.java
@@ -724,7 +724,7 @@
         org.eclipse.equinox.internal.p2.engine.phases.AuthorityChecker.class.getName();
         enabled = true;
       }
-      catch (Exception ex)
+      catch (Throwable ex)
       {
         //$FALL-THROUGH$
       }