issue #16: rearrange Travis matrix and add Python 3.6 target for core tests

.travis.yml

@@ -7,11 +7,21 @@ notifications:
   email: false
 
 language: python
+
 cache:
 - pip
 - directories:
   - /home/travis/virtualenv
 
+install:
+- pip install -r dev_requirements.txt
+
+script:
+- ${TRAVIS_BUILD_DIR}/.travis/${MODE}_tests.sh
+
+services:
+  - docker
+
 matrix:
   include:
     # Mitogen tests.
@@ -27,6 +37,9 @@ matrix:
     # 2.6 -> 2.6
     - python: "2.6"
       env: MODE=mitogen DISTRO=centos6
+    # 3.6 -> 2.7
+    - python: "3.6"
+      env: MODE=mitogen DISTRO=debian
 
     # Debops tests.
     # 2.4.3.0; 2.7 -> 2.7
@@ -35,6 +48,9 @@ matrix:
     # 2.5.5; 2.7 -> 2.7
     - python: "2.7"
       env: MODE=debops_common VER=2.5.5
+    # 2.5.5; 3.6 -> 2.7
+    - python: "3.6"
+      env: MODE=debops_common VER=2.5.5
 
     # ansible_mitogen tests.
     # 2.4.3.0; Debian; 2.7 -> 2.7
@@ -55,16 +71,10 @@ matrix:
     # 2.5.5; CentOS; 2.6 -> 2.6
     - python: "2.6"
       env: MODE=ansible VER=2.5.5 DISTRO=centos6
+    # 2.5.5; Debian; 3.6 -> 2.7
+    - python: "3.6"
+      env: MODE=ansible VER=2.5.5 DISTRO=centos6
 
     # Sanity check our tests against vanilla Ansible, they should pass.
     - python: "2.7"
       env: MODE=ansible VER=2.5.5 DISTRO=debian STRATEGY=linear
-
-install:
-- pip install -r dev_requirements.txt
-
-script:
-- ${TRAVIS_BUILD_DIR}/.travis/${MODE}_tests.sh
-
-services:
-  - docker