options --exists work incorrect (fixed)

[Incont]

$ ios-deploy --version
1.6.1
$ ios-deploy --exists --bundle_id com.test.test
[....] Waiting for iOS device to be connected
[....] Using iPad 2 'test' (xxxxxxxfdfd3099858b2fd5c8d7e9accc27c9405) xxxxxxxfdfd3099858b2fd5c8d7e9accc27c9405).

$ ios-deploy --exists --bundle_id com.test.test --id xxxxxxxfdfd3099858b2fd5c8d7e9accc27c9405
[....] Waiting for iOS device to be connected
[....] Using iPad 2 'test' (xxxxxxxfdfd3099858b2fd5c8d7e9accc27c9405) (xxxxxxxfdfd3099858b2fd5c8d7e9accc27c9405).

[Incont]

Fixes #134