add tests for the new MHD Roe solver

[ranocha]

This is a regression test for the MHD Roe solver implemented in clawpack/riemann/pull/155.

[coveralls]

Coverage remained the same at ?% when pulling 1bd079b on ranocha:mhd_roe into 2e9d3a7 on clawpack:master.

[coveralls]

Coverage remained the same at ?% when pulling 5002e91 on ranocha:mhd_roe into 2e9d3a7 on clawpack:master.

[coveralls]

Coverage remained the same at ?% when pulling 5002e91 on ranocha:mhd_roe into 2e9d3a7 on clawpack:master.

[ranocha]

I wouldn't have expected the tests to pass since the new MHD Roe solver is not merged to clawpack/riemann yet. The tests on Travis do not seem to run the new example. Is this intended behavior?

[mandli]

It should be running it but it does not look like the test is being found. When you run nosetest does it find your test?

[ketch]

I think there was an issue with the example test I suggest you start with (oops!) I've opened a PR that I believe fixes this PR.

[ranocha]

Thanks, @ketch! I've merged your PR.

[ketch]

Looks like I didn't fix it; it's still not picking up the test. I'll investigate.

[ketch]

I've made another PR to your branch (after actually testing it this time!)

[ranocha]

Thanks! I've merged your PR.