Run make acronyms in Travis

As of DM-13140, the lsst-texmf Docker image contains the dependencies
necessary to run acronyms.csh.

I think that make acronyms needs to be run explicitly since it isn't
being triggered by `make all` (and since an acronyms.tex is checked into
the repo, not forcing local writers to run acronyms.csh is likely more
portable).

.travis.yml

@@ -13,6 +13,8 @@ script:
    # Prepare document dependencies in Travis (Python 3.5) environment
    - "make wbslist.tex"
    - "make ProductTree.tex"
+   # Ensure acronyms are built
+   - "docker run --rm -v `pwd`:/workspace -w /workspace lsstsqre/lsst-texmf:latest sh -c 'make acronyms'"
    # Compile LaTeX using containerized lsst-texmf.
    # Make targets that rely on Python should be no-ops at this point.
    - "docker run --rm -v `pwd`:/workspace -w /workspace lsstsqre/lsst-texmf:latest sh -c 'make all'"