Tweaks to material writting methods for MCNP and ALARA to return strings.
Fixed mcnp and alara Material methods naming.
Reimplimented write_mcnp and write_alara and corresponding tests.
Merge pull request #283 from elliottbiondo/mat_str

Material methods to return MCNP and ALARA strings.
Merge branch 'staging' of https://github.com/pyne/pyne into mcnp_mesh
Working version of mesh_to_geom.