src: Replace Tokenizer with the methods of ndn::Name

Purpose of this commit is to replace Tokenizer in all
places except conf-file-processor.*pp with the methods
of ndn::Name. One static method in class NameHelper
is added. Tokenizer will be removed finally when
configuration file parsing commit is complete.

Refs: 1533

Change-Id: I14a67655eb963c5cc5b045c3c9f7d516e405ff19