Move back to using Chrome on OSX closes #2043

This moves back to using Chrome on OSX but making it obvious that it's Chrome to avoid any user issues with running Chrome itself. This also includes a more general refactoring of the browser launching code, as it had gotten a little convoluted after various revisions. This should be a bit more maintainable and portable.
This stuff is mysterious to me, but for whatever reason if I make this call from a LanternUtils static method for a resource at the root, the getSystemResourceAsStream call would return null while the LanternUtils.class.getResourceAsStream call would not. That was actually for when I was experimenting with using an AppleScript snippet to determine the default browser, which came to seem like not the best option, but the change does make the call more robust.