Error Message: App can’t be opened because it is from an unidentified developer

Disable Gatekeeper blocking unidentified apps in OS X Mountain Lion

  1. Launch System Preferences from the Apple menu
  2. Choose “Security & Privacy” and then click the “General” tab, followed by clicking the lock icon in the corner to unlock the settings
  3. Look for “Allow applications downloaded from:” and choose “Anywhere”
  4. Accept the security warning and allow
  5. You can now launch any app from any location or developer