Try harder to get application's name.

CFBundleDisplayName may lack localization or may be missing altogether
(default Info.plist files created by Xcode don't have it).  Try to use
non-localized entry or CFBundleName as fallbacks.  This is similar to
what e.g.  Sparkle does.
Merge pull request #2 from vslavik/appname-try-harder

Attempts multiple InfoList dictionary keys to get application's name.