Test script for the newly added 3D Euler Equations using F-Wave

Adding a hot sphere rising in a stabilized equilibrium atmosphere for the 3D Euler equations in Cartesian coordinates.  Riemann solver added with PR: clawpack/riemann#85
Test script for the newly added 3D Euler Equations using F-Wave in Spherical Coordinates

Adding a hot sphere rising in a stabilized equilibrium atmosphere for the 3D Euler equations in Earth centered spherical coordinates.  Riemann solver added with PR: clawpack/riemann#85
Merge branch 'master' into rising_hot_sphere_examples