Revert "CI: Temporarily drop all other tests"

This reverts commit 12b2ad1.

Author: effigies

appveyor.yml

@@ -5,9 +5,19 @@ environment:
   DEPENDS: numpy scipy matplotlib h5py pydicom
 
   matrix:
+    - PYTHON: C:\Python27
+    - PYTHON: C:\Python27-x64
+    - PYTHON: C:\Python34
+    - PYTHON: C:\Python34-x64
+    - PYTHON: C:\Python35
+    - PYTHON: C:\Python35-x64
     - PYTHON: C:\Python35-x64
       PYTHONHASHSEED: 283137131
       DEPENDS: "h5py==2.9.0"
+    - PYTHON: C:\Python36
+    - PYTHON: C:\Python36-x64
+    - PYTHON: C:\Python37
+    - PYTHON: C:\Python37-x64
 
 install:
   # Prepend newly installed Python to the PATH of this build (this cannot be