(CMake ROSE) make install on Linux

* We can now run "make install" from our Linux binary directory and have
  it complete successfully (without error).  This does not mean that
  we're installing everything we need for a meaningful distribution of
  ROSE.  It just means that "make install" no longer results in an error.

* Installed header files now honor CMAKE_INSTALL_PREFIX.  Previously they
  were hardcoded to be installed in /usr/include .