Fixed conditionals for docker herkou and rvm installs

roles/developer-machine/tasks/main.yml

@@ -4,22 +4,24 @@
 - name: Is rvm installed
   shell: which rvm
   register: rvm_installed
+  failed_when: "rvm_installed.rc == 2 or rvm_installed.rc == 3"
 
 - name: Install rvm key
   shell: gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3
-  when: rvm_installed is none
+  when: rvm_installed.stdout == ""
 
 - name: Install rvm and latest ruby
   shell: \curl -sSL https://get.rvm.io | bash -s stable
-  when: rvm_installed is none
+  when: rvm_installed.stdout == ""
 
 - name: Is heroku installed
   shell: which heroku
   register: heroku_installed
+  failed_when: "heroku_installed.rc == 2 or heroku_installed.rc == 3"
 
 - name: Install heroku toolbelt
   shell: wget -O- https://toolbelt.heroku.com/install-ubuntu.sh | sh
-  when: heroku_installed is none
+  when: heroku_installed.stdout == ""
 
 - name: Install siege
   apt: name=siege state=present