Add linux python 3.6 builds

Author: jorisvandenbossche

.travis.yml

@@ -60,6 +60,17 @@ matrix:
         - PLAT=i686
         - NP_BUILD_DEP=numpy==1.9.3
         - NP_TEST_DEP=numpy==1.9.3
+    - os: linux
+      env:
+        - MB_PYTHON_VERSION=3.6
+        - NP_BUILD_DEP=numpy==1.9.3
+        - NP_TEST_DEP=numpy==1.9.3
+    - os: linux
+      env:
+        - MB_PYTHON_VERSION=3.6
+        - PLAT=i686
+        - NP_BUILD_DEP=numpy==1.9.3
+        - NP_TEST_DEP=numpy==1.9.3
     - os: osx
       language: generic
       env: MB_PYTHON_VERSION=2.7