build: Add optional pthread flag when detecting Crypto++

This commit also includes a small fix to support Python3

Change-Id: Ifa0c547bd872ab749745b5bdc778d4b3269bb87e
Refs: #1590
build: Correcting library detection

When detecting location of the library, `includes` and `libpath`
variables must be used instead of `cxxflags` and `linkflags`.  While the
latter also makes everything work, it results in unexpected behavior:
waf always adds LINKFLAGS* in the beginning of the linking command,
which can screw up order in which libraries are selected (e.g.,
system-installed library can be chosen instead of the compiled version).

Change-Id: I9ed36e8a4e8523b33ca2e88414aed8de5111c9cd
build: Disable building examples by default

To enable examples, one need to use `--with-examples` configure flag.
Note about this added to the getting started instructions.

Change-Id: If9afb1fd3f298b634adb8bb3a4bcae151ac8f7af
src: Removing unnecessary use of cref() in concert with make_shared

This commit also replaces all usages of shared_ptr<T>(new T) with
make_shared<T> in Face class implementation.

Change-Id: I44971c44eb7f2c25ecfe00e185309973c9cbd246
Refs: #1592
src: Removing deprecated logging facility

This commit removes last usages of logging facility and removes the
facility all together.  At some point in the future we may add logging
back, but it should be something that is depends and configured from
the application.

Change-Id: I10bd94aea05f127041d68cb77a77eb96e929c880
docs: Updating doxygen comments and minor update to normalize API

Change-Id: I24686acc36f372ee2eddffaaa6c104f964ceeca4
Refs: #1299
src: Refactoring common.hpp and minimizing exposed includes

Face class has relatively large rewrite to hide internals using
Implementor pattern.  As of this commit, <boost/asio.hpp> is not
automatically included whenever ndn-cxx/face.hpp is included.  If it is
needed to directly work with io_service, asio.hpp should be specifically
included.

Change-Id: Ie742b851025b4e3da634eb981319df0f42937855
src: Making use of DEPRECATED macro and updating library code not to use deprecated methods

Change-Id: Ibe17977e7fcbb759a26dbe1cfa3d472598e49bcc
build: Reviving support for precompiled headers

This commit also includes an update of ./waf, which has several
improvements.  In particular, clang++ is now default compiler on OSX
platform.

Change-Id: I4c171c04d18e9cb83e461264a35b9ed85ea4d50e