Remove the python-httplib2 dependency

Rather than check the remote VERSION with the 'uri' Ansible module
I decided to just always run rvm update unless you specifically disable
that in the default options.

The benefits of this change is that the role no longer depends on any
packages and CentOS 7 does not have python-httplib2 anyways.

The cons of this change is that the update takes an additional 2-3
seconds to run when it was skipped previously unless needed. However, with the
elimination of quite a few tasks and logic the overall run speed of the
role is faster than before.

README.md

@@ -40,16 +40,14 @@ rvm1_install_path: '/usr/local/lib/rvm'
 #       make sure you ADD the --user-install flag below
 rvm1_install_flags: '--auto-dotfiles'
 
-# Should rvm always be upgraded?
-rvm1_rvm_force_upgrade_installer: False
-
-# URLs for the latest installer and version
+# URL for the latest installer script
 rvm1_rvm_latest_installer: 'https://raw.githubusercontent.com/wayneeseguin/rvm/master/binscripts/rvm-installer'
-rvm1_rvm_stable_version_number: 'https://raw.githubusercontent.com/wayneeseguin/rvm/master/VERSION'
 
-# Time in seconds before re-running apt-get update
-# This is only used to download the httplib library so Ansible's URI module works
-apt_cache_valid_time: 86400
+# rvm version to use
+rvm1_rvm_version: 'stable'
+
+# Check and update rvm, disabling this will force rvm to never update
+rvm1_rvm_check_for_updates: True
 ```
 
 ## Example playbook