Use pandoc 2.1.3

Author: chdemko

.travis.yml

@@ -5,8 +5,8 @@ python:
   - "3.4"
   - "3.5"
 before_install:
-  - wget https://github.com/jgm/pandoc/releases/download/2.1.2/pandoc-2.1.2-1-amd64.deb
-  - sudo dpkg -i pandoc-2.1.2-1-amd64.deb
+  - wget https://github.com/jgm/pandoc/releases/download/2.1.3/pandoc-2.1.3-1-amd64.deb
+  - sudo dpkg -i pandoc-2.1.3-1-amd64.deb
   - pandoc -v
 install:
   - pip install coveralls