Update README and acceptance spec helper

Call out the fact that `apt-transport-https` is a pre-requisite, and
update the acceptance test spec helper to make sure this is installed.

Author: yankcrime

README.md

@@ -22,6 +22,10 @@ There's a couple of fairly standard dependencies for this module, as follows:
 * https://github.com/puppetlabs/puppetlabs-stdlib
 * https://github.com/puppetlabs/puppetlabs-apt (on Debian / Ubuntu)
 
+*NB:* On some apt-based distributions you'll need to ensure you have support
+for TLS-enabled repos in place.  This can be achieved by installing the
+`apt-transport-https` package.
+
 ### Usage
 
 Telegraf's configuration is split into four main sections - global tags,

spec/acceptance/nodesets/ubuntu1404.yml

@@ -0,0 +1,10 @@
+HOSTS:
+  ubuntu-server-1404-x64:
+    platform: ubuntu-14.04-amd64
+    box : puppetlabs/ubuntu-14.04-64-nocm
+    box_url : https://vagrantcloud.com/puppetlabs/ubuntu-14.04-64-nocm
+    hypervisor : vagrant
+CONFIG:
+  masterless: true
+  log_level: verbose
+  type: git

spec/spec_helper_acceptance.rb

@@ -21,6 +21,9 @@
     puppet_module_install(:source => proj_root, :module_name => 'telegraf')
     # Install dependancies
     hosts.each do |host|
+      if fact('osfamily') == 'Debian'
+        on host, 'apt-get -y install apt-transport-https'
+      end
       on host, puppet('module', 'install', 'puppetlabs-stdlib'), { :acceptable_exit_codes => [0,1] }
       on host, puppet('module', 'install', 'puppetlabs-apt'), { :acceptable_exit_codes => [0,1] }
     end