unhandled error when libimobiledevice tools not installed

[ahoog42]

Should handle this better, offer tip to user to check to make sure libimobiledevice tools are installed and in current path.

  ios-triage extract .
events.js:163
      throw er; // Unhandled 'error' event
      ^

Error: spawn idevice_id ENOENT
    at exports._errnoException (util.js:1050:11)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:193:32)
    at onErrorNT (internal/child_process.js:367:16)
    at _combinedTickCallback (internal/process/next_tick.js:80:11)
    at process._tickCallback (internal/process/next_tick.js:104:9)
    at Module.runMain (module.js:607:11)
    at run (bootstrap_node.js:427:7)
    at startup (bootstrap_node.js:151:9)
    at bootstrap_node.js:542:3```