Pin get-pip.py to last Python 3.5 version

We only support Puppet versions available for platforms up through
Ubuntu Xenial, which provides Python 3.5 as its python3 interpreter.
Recently pip, and by extension get-pip.py, ceased supporting Python
<3.6 but added stable URLs for the last releases to support earlier
interpreters. Switch to the URL for a get-pip.py which will still
work for Xenial servers.

Also fix a couple of new linter failures.

Change-Id: I042bfc330e4d562313cf0dbf2be7d0e2d5779f40

manifests/init.pp

@@ -6,7 +6,7 @@ class pip (
   $optional_settings = {},
   $trusted_hosts     = [],
 ) {
-  include ::pip::params
+  include pip::params
   validate_array($trusted_hosts)
 
   package { $::pip::params::python_devel_package:

manifests/params.pp

@@ -3,7 +3,7 @@
 # This class holds parameters that need to be
 # accessed by other classes.
 class pip::params {
-  $get_pip_location = 'https://bootstrap.pypa.io/get-pip.py'
+  $get_pip_location = 'https://bootstrap.pypa.io/3.5/get-pip.py'
 
   case $::osfamily {
     'RedHat': {

manifests/python3.pp

@@ -1,7 +1,7 @@
 # Class: pip
 #
 class pip::python3 {
-  include ::pip::params
+  include pip::params
 
   package { $::pip::params::python3_devel_package:
     ensure => present,