Bump minimal Ansible version to 1.6

And do not use wheel for Ansible installation, since this causes problems in Ansible <= 1.8

.travis.yml

@@ -35,23 +35,6 @@ env:
   - ANSIBLE_VERSION=1.6.10
   - ANSIBLE_VERSION=1.6.1
   - ANSIBLE_VERSION=1.6
-  - ANSIBLE_VERSION=1.5.5
-  - ANSIBLE_VERSION=1.5.4
-  - ANSIBLE_VERSION=1.5.3
-  - ANSIBLE_VERSION=1.5.2
-  - ANSIBLE_VERSION=1.5.1
-  - ANSIBLE_VERSION=1.5
-  - ANSIBLE_VERSION=1.4.5
-  - ANSIBLE_VERSION=1.4.4
-  - ANSIBLE_VERSION=1.4.3
-  - ANSIBLE_VERSION=1.4.2
-  - ANSIBLE_VERSION=1.4.1
-  - ANSIBLE_VERSION=1.4
-
-matrix:
-  allow_failures:
-    # See https://github.com/ansible/ansible/issues/6385
-    - env: ANSIBLE_VERSION=1.5.1
 
 branches:
   only:
@@ -65,7 +48,7 @@ before_install:
 
 install:
   # Install Ansible.
-  - if [ "$ANSIBLE_VERSION" = "latest" ]; then pip install ansible; else pip install ansible==$ANSIBLE_VERSION; fi
+  - if [ "$ANSIBLE_VERSION" = "latest" ]; then pip install --no-binary ansible ansible; else pip install --no-binary ansible ansible==$ANSIBLE_VERSION; fi
 
 script:
   # Check the role/playbook's syntax.

meta/main.yml

@@ -5,7 +5,7 @@ galaxy_info:
   company: Oefenweb.nl B.V.
   description: Set up cron-apt in Debian-like systems
   license: MIT
-  min_ansible_version: 1.4
+  min_ansible_version: 1.6
   platforms:
     - name: Ubuntu
       versions: