Revert "TMP: remove long tests to get wheel build"

This reverts commit 392371688b.

.travis.yml

@@ -29,6 +29,13 @@ script:
     - cd Pillow
     - python selftest.py --installed
     - pip install nose
+    - export NOSE_PROCESS_TIMEOUT=600
+    - export NOSE_PROCESSES=-1
+    - if [ -f test-installed.py ]; then
+      python test-installed.py ;
+      else
+      python Tests/run.py --installed ;
+      fi
     - cd ..
 
 before_deploy: cd Pillow/dist