Cleanup catch Exception when making Java7FSFactory

Cleanup catch Exception when making Java7FSFactory

Catching Exception and rethrowing as Error when the Java7 factory was
not available threw an unexpected error to the caller, but then
confused things by still setting the factory to the default Java
5 version.  A second call to FS.detect(Boolean) would succeed.

Do not throw to the caller. Instead always default to the Java5
factory if the Java7 one is not loading.

Change-Id: I6e9edb257b404d213ff08c44560fdb1672a5c80b