Improving async operations and error reporting

All operations, including connect are fully async

Change-Id: I6c28c4f883d3aa10efbc4af939cf09e0e865c574
Small complication to allow (in future) aggregation of Face processing threads

Change-Id: Ia318d4cee7da7ed1e0f069409e86f3e12f62b816
Moving osx private key storage out of disabled

Change-Id: Ie7ea8573e898022c1661d05907d577631ecedb77
Signature interface change and initial fixes for OSX private key store

Change-Id: I6f927da2606cb5fb383e55d335cd8e8c6c118bda
Change in KeyChain creation API

Also, enabling creation of default public/private storages

Change-Id: I13230ac3f8b397ad4bedfe29b871f8cafa9afff5
Name: allow negative argument for 'get' method to get component from the back

Change-Id: I7e76fc16dfc5ce8ed2a18cfb461f884b82e1b274
IdentityStorage: copying ndn.cxx extensions to get information about the stored data

Change-Id: Id272a4985a6caa3ddfdc177ebf1b318b351279f8
Extensions to simplify coding

Change-Id: I69a123e2d2770127ad5e7d0a8a5e5ef714d5da4f