Default shade_pip_executable to pip3

Moving forward, we'll only support shade under python3. While shade
still supports python2, this role will only support python3.

Users still have the ability to install python2, but will need to do
more work to make that happen.

Change-Id: I2970b76db9dc6badb9e720e5795abcda761fb2d4
Signed-off-by: Paul Belanger <pabelanger@redhat.com>

README.rst

@@ -17,6 +17,8 @@ Shade is a simple client library for operating OpenStack clouds.
 Requirements
 ------------
 
+* pip3 to be installed if using shade_install_method: (git|pip)
+
 See `bindep.txt` for role dependencies.
 
 Packages

tasks/install.yaml

@@ -25,4 +25,12 @@
   with_items: "{{ shade_build_depends }}"
   when: shade_install_method == 'git' or shade_install_method == 'pip'
 
+- name: Define shade_pip_executable if needed.
+  set_fact:
+    shade_pip_executable: pip3
+  when:
+    - shade_install_method == 'git' or shade_install_method == 'pip'
+    - shade_pip_virtualenv_python is not defined
+    - shade_pip_executable is not defined
+
 - include: "install/{{ shade_install_method }}.yaml"

vars/Debian.yaml

@@ -15,4 +15,4 @@
 __shade_build_depends:
   - gcc
   - libssl-dev
-  - python-dev
+  - python3-dev

vars/RedHat.yaml

@@ -15,4 +15,4 @@
 __shade_build_depends:
   - gcc-c++
   - openssl-devel
-  - python-devel
+  - python3-devel