List of changes:
* -I boost is no longer required
(Since the use of Boost::xxx imported targets)
* fix missing Boost deps in imported gtsam by
searching for Boost inside GTSAMConfig.cmake
* Including the dirs for Eigen/MKL/SuiteSparse/Metis
into exported targets public interface.
* Fix missing cmake changes in wrap/*
* Split build flags into private/public, not to
expose to users flags that may be invasive.
* Removed now useless include_dirs in "extra cmake"
* Update cmake/example_project
* Make cppunitlite to find boost headers via Boost::boost
* Update README / INSTALL to reflect the updated minimum CMake >= 3.0