sync: In ChronoSync2013, move the work into the Impl inner class which inherits enable_shared_from_this. Refs #2134.
sync (internal): In ChronoSync2013::Impl, call registerPrefix and expressInterest in a separate initialize() method. Refs #2134.
sync (internal): In ChronoSync2013::Impl, when passing a callback, replace all "this" with shared_from_this() so that the callback function object keeps its own reference. Refs #2134.
tests: In test-chrono-chat, make the Chat object belong to a shared_ptr and split out initialize() from the constructor. Refs #2134.
tests: In test-chrono-chat, when passing a callback, replace "this" with shared_from_this() so that the callback function shares a reference. Refs #2134.
CHANGELOG: Added bug #2134. Refs #2134.
Merge branch 'issue/2134-ChronoSync2013-shared_ptr-for-callbacks'. Refs #2134.
http://redmine.named-data.net/issues/2134