Minimise distro packages installed

The current package install set is quite broad
for xenial. This reduces the set and ensures that
the pip packages installed are appropriate based
on the python version used for each distro.

ndg-httpsclient specifically is only required
for python<2.7.9

Change-Id: I65d05f6fd187b896e5e710f9d95f89bf769ecc60

vars/redhat-7.yml

@@ -20,12 +20,12 @@ pip_install_distro_build_packages:
   - libffi-devel
   - openssl-devel
   - python-devel
-  - python-pyasn1
-  - python2-pyOpenSSL
   - yum-plugin-priorities
 
 pip_required_pip_packages:
   - ndg-httpsclient # SSL SNI support
+  - pyasn1 # SSL SNI support
+  - pyOpenSSL # SSL SNI support
   - requests # SSL SNI support
   - urllib3 # SSL SNI support
 

vars/suse-42.yml

@@ -22,10 +22,10 @@ pip_install_distro_build_packages:
   - libffi-devel
   - libopenssl-devel
   - python-devel
-  - python-pyasn1
-  - python-pyOpenSSL
 
 pip_required_pip_packages:
   - ndg-httpsclient # SSL SNI support
+  - pyasn1 # SSL SNI support
+  - pyOpenSSL # SSL SNI support
   - requests # SSL SNI support
   - urllib3 # SSL SNI support

vars/ubuntu-16.04.yml

@@ -20,15 +20,14 @@ uca_repo: "deb {{ uca_apt_repo_url }} {{ uca_repo_dist }} main"
 pip_install_external_repo_key_package: "ubuntu-cloud-keyring"
 
 pip_install_distro_build_packages:
-  - build-essential
+  - gcc
   - python-dev
-  - python-setuptools
   - libffi-dev
   - libssl-dev
   - python3-dev
-  - python-openssl
-  - python-pyasn1
 
 pip_required_pip_packages:
-  - urllib3 # SSL SNI support
+  - pyasn1 # SSL SNI support
+  - pyOpenSSL # SSL SNI support
   - requests # SSL SNI support
+  - urllib3 # SSL SNI support