Move lalinference executables from lalapps to lalinference

@adam-mercer, @vivien and I would like to try and move all of the remaining lalinference code (mainly executables) out of lalapps and into the lalinference package. This is mainly to clean up dependencies, so that people don't have to install lalapps to run lalinference_mcmc.

This would then require adding an openmpi dependency to lalinference, are there any gotchas we should be aware of when doing that, and how much work do you think it would be?