Install pandoc during tests on Travis and Appveyor

Author: nnicandro

.travis.yml

@@ -39,6 +39,8 @@ install:
   # /usr/local/share/jupyter. This installs one with an absolute path using our
   # python3
   - sudo python3.6 -m ipykernel.kernelspec
+  # Install additional packages needed by the tests
+  - sudo apt-get install pandoc
 before_script:
   # Ensure Jupyter runtime dir can be written to
   - mkdir -p $(jupyter --runtime-dir)

appveyor.yml

@@ -33,6 +33,8 @@ install:
   - if not exist C:\Miniconda3-x64\envs\jupyter conda create --name jupyter python=%JUPYTER_PYTHON_VERSION%
   - conda activate jupyter
   - conda install jupyter
+  # Install additional packages needed by tests
+  - conda install -c conda-forge pandoc
   # Ensure Jupyter runtime dir can be written to
   - ps: mkdir -p (jupyter --runtime-dir)
   - jupyter --version