added abstract class for initialization
initial implementation of VXL camera/landmark init

currently does not to do camera scale or landmarks
adjust pose relative to previous camera
throw exception on missing inputs and algorithms
started tests for initialization algo
Recover scale of estimated translation vector

Use triangulation of points and 2D-3D correspondence to recover scale.
better handling of landmark initialization
added tests for landmark locations
added tests for subset initialization
use the closest frame, not always the last
added initialization to bundle adjust tool
Added release notes for camera initialization
Fixed build and install CMake config configuration

+ added install location comment in install CMake config template for
  pathing reference.
Added release note.
Merge pull request #23 from Purg/dev/fix-cmake-config

Dev/fix cmake config
Merge branch 'release'

* release:
  Added release note.
  Fixed build and install CMake config configuration
check if OpenCV was built with non-free enabled
Default to ORB instead of SURF in case nonfree is disabled
need to include opencv_modules.hpp
Try SURF first, but fall back to ORB if OpenCV does not have nonfree