* Fixes for libbeagle
This PR fixes a couple of issues with the libbeagle package.
- Use args.append('--with-cuda=%s' % self.spec['cuda'].prefix)
- Disable the default of compiling with -march=native as Spack now
  inserts architecture specific flags
- Set BEAST_LIB in the beast1 package not in libbeagle.
* Use new setup_run_environment method