Tell Travis CI to use multiple cores

Let’s see if this helps the build go faster

.travis.yml

@@ -47,7 +47,7 @@ install:
 
 script:
 - mv ocrmypdf dont_import_this_ocrmypdf
-- pytest
+- pytest -n auto
 - mv dont_import_this_ocrmypdf ocrmypdf
 
 deploy:

setup.cfg

@@ -11,3 +11,4 @@ ignore =
 [tool:pytest]
 norecursedirs = lib .pc .git output cache resources
 testpaths = tests
+addopts = -n auto

test_requirements.txt

@@ -1,2 +1,3 @@
 pytest >= 3.0
-pytest-helpers-namespace
+pytest-helpers-namespace
+pytest-xdist