Make dependencies for component libraries as optional
Make dependencies for component libraries as optional

Here is a quick summary of the dependencies.

- mandatories for core library: eigen, ccd, fcl, assimp, boost
- optional for component libraries:
  - dart-optimizer: nlopt, ipopt
  - dart-collision: bullet
  - dart-planning: flann
  - dart-utils: tinyxml, tinyxml2, urdfdom
  - dart-gui: opengl, glut, openscenegraph

axeisghost/DART6motionBlur,dartsim/dart,dartsim/dart,axeisghost/DART6motionBlur,dartsim/dart,dartsim/dart,axeisghost/DART6motionBlur,dartsim/dart