remove duplicate 3d variable-coefficient acoustics riemann solvers.
Merge pull request #23 from ketch/rm_dupes

remove duplicate 3d variable-coefficient acoustics riemann solvers.
Add 3d Euler solvers.
Fix typo.
Merge pull request #24 from ketch/3d_euler

Add 3d Euler solvers.
Riemann build system cleanup - Added Travis configuration
adding LAPACK install to Travis configuration
Merge pull request #27 from ahmadia/setup_refactor

Riemann build system cleanup - Added Travis configuration
Remove debug print statement.
merged from upstream to rjleveque