Attempt at detecting and fixing simulator namespace related failure

This is an attempt to detect and fix the namespace problem found in issues #285 and #162. The test here uses launchctl to probe for quicklook entries and then ask for the configuration of each entry, if one of the info requests succeeds the assumption is that the correct namespace is currently available. I picked quicklook since it seems likely that it is always available. If reattach-to-user-namespace can be found it is used otherwise a warning message is printed. I haven't done extensive testing with this so I can't say exactly how reliable the test is.