disable travis mac builders and add a mac jenkins build (#3933)

we'll re-enable mac builders when travis recovers and remove the jenkins
build
diff --git a/.travis.yml b/.travis.yml
index 4bf0053..a2cafef 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -49,46 +49,46 @@
           env: TOXENV=pep8
         - python: 3.4
           env: TOXENV=py3pep8
-        - language: generic
-          os: osx
-          # 8.3 is macOS 10.12.x
-          # see: https://docs.travis-ci.com/user/osx-ci-environment/
-          osx_image: xcode8.3
-          env: TOXENV=py27 CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1
-        - language: generic
-          os: osx
-          osx_image: xcode8.3
-          env: TOXENV=py34 CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1
-        - language: generic
-          os: osx
-          osx_image: xcode8.3
-          env: TOXENV=py35 CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1
-        - language: generic
-          os: osx
-          osx_image: xcode8.3
-          env: TOXENV=py36 CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1
-        - language: generic
-          os: osx
-          osx_image: xcode8.3
-          env: TOXENV=pypy-nocoverage CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1 PYPY_VERSION=pypy2.7-5.8.0
-        - language: generic
-          os: osx
-          osx_image: xcode8.3
-          env: TOXENV=py27 CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=0
-        - language: generic
-          os: osx
-          # 7.3 is OS X 10.11.x
-          osx_image: xcode7.3
-          env: TOXENV=py27 CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1
-        - language: generic
-          os: osx
-          # 6.4 is OS X 10.10.x
-          osx_image: xcode6.4
-          env: TOXENV=py27 CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1
-        - language: generic
-          os: osx
-          osx_image: xcode8.3
-          env: TOXENV=docs CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1
+        # - language: generic
+        #   os: osx
+        #   # 8.3 is macOS 10.12.x
+        #   # see: https://docs.travis-ci.com/user/osx-ci-environment/
+        #   osx_image: xcode8.3
+        #   env: TOXENV=py27 CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1
+        # - language: generic
+        #   os: osx
+        #   osx_image: xcode8.3
+        #   env: TOXENV=py34 CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1
+        # - language: generic
+        #   os: osx
+        #   osx_image: xcode8.3
+        #   env: TOXENV=py35 CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1
+        # - language: generic
+        #   os: osx
+        #   osx_image: xcode8.3
+        #   env: TOXENV=py36 CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1
+        # - language: generic
+        #   os: osx
+        #   osx_image: xcode8.3
+        #   env: TOXENV=pypy-nocoverage CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1 PYPY_VERSION=pypy2.7-5.8.0
+        # - language: generic
+        #   os: osx
+        #   osx_image: xcode8.3
+        #   env: TOXENV=py27 CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=0
+        # - language: generic
+        #   os: osx
+        #   # 7.3 is OS X 10.11.x
+        #   osx_image: xcode7.3
+        #   env: TOXENV=py27 CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1
+        # - language: generic
+        #   os: osx
+        #   # 6.4 is OS X 10.10.x
+        #   osx_image: xcode6.4
+        #   env: TOXENV=py27 CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1
+        # - language: generic
+        #   os: osx
+        #   osx_image: xcode8.3
+        #   env: TOXENV=docs CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1
 
 install:
     - ./.travis/install.sh
diff --git a/Jenkinsfile b/Jenkinsfile
index 8742e85..92b0c7e 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -17,7 +17,7 @@
     ],
     [
         label: 'sierra',
-        toxenvs: ['py27'],
+        toxenvs: ['py27', 'py36'],
     ],
     [
         label: 'yosemite',