Dockerized ED2 fails with MPI error messages

[ashiklom]

Describe the bug
Dockerized ED2 crashes immediately with a bunch of cryptic OpenMPI-related error messages.

To Reproduce
Run Dockerized ED2 (git).

Expected behavior
Model should at least initialize and fail with ED-related errors. These errors come before ED logs any output.

Machine (please complete the following information):
Docker.

Temporary Workaround
Edit the models/ed/inst/template.job file so that the @BINARY is called as @BINARY -s. AFAICT, @robkooper added the -s flag to delay MPI initialization in ED, which seems to fix the problem. Note that you will then have to rebuild the pecan/base and pecan/executor images to make these changes take effect.

A nicer, more-permanent fix might be to allow users to pass additional flags to the model binary via pecan.xml. We already have a <binary> tag -- it should be easy to add an optional <binary-flags> tag and then change our template.job to call @BINARY as @BINARY @BINARYFLAGS.