Rename code file ndn.js to face.js. Refs #1071
Rename class NDN to Face and define a deprecated class NDN which inherits from it.
Use Face instead of NDN class. Use variable name face instead of ndn. Refs #1071.
In Upcall, rename member ndn to face.  Add deprecated member ndn. Refs #1071.
CHANGELOG: Added issue 1071 Renamed the main NDN class to Face. Refs #1071.
Merge branch 'issue/1071-rename-NDN-to-Face'. Refs #1071.
http://redmine.named-data.net/issues/1071