mini-ndn

Currently, the Mini-NDN nfdc helper code does not correctly handle the "face-updated" response in nfdc, which occurs when a face exists but "nfdc face create" is called with differing parameters to it. Currently, NLSR can trigger the creation of a face in other nodes via mechanisms in the NFD UDP channel implementation (and likely other face types) due to NFD creating a non-permanent face in response to Hello traffic. As the NLSR faces created are permanent, this causes this unexpected output. Given that "allowExisting" is already an argument passed in, we should likely just suppress this causing an error if this flag is set. However, we can also prevent this from occurring via making some adjustments to the app manager and NLSR classes to do face creation in the latter's initialization step and only starting processes after nodes are initialized.