Add benchmark svgs, and os: linux to Documenter build.

Author: chriselrod

.travis.yml

@@ -17,6 +17,7 @@ jobs:
   include:
     - stage: Documentation
       julia: 1.3
+      os: linux
       script: julia --project=docs -e '
           using Pkg;
           Pkg.develop(PackageSpec(path=pwd()));