Cert Location Setting and Recently Used Strings

[benmartens]

1. The certificate button for SNI auth now looks only at one location (either CurrentUser or LocalMachine) based on field in the Settings dialog.
2. The 10 most recently used cluster, database, and app ids are now stored in the user settings file and the list is updated each time a valid comparison is completed. Users can ignore this feature by continuing to type in their own strings or they can use the drop downs to populate a particular field.