Fix nginx package installation (#157)

tasks/installation.packages.yml

@@ -1,15 +1,15 @@
 ---
-- name: Install the epel packages
+- name: Install the epel packages for EL distributions
   package: name=epel-release state=present
   when: nginx_is_el|bool and nginx_install_epel_repo|bool
 
-- name: Install the nginx packages from official repo
+- name: Install the nginx packages from official repo for EL distributions
   yum: name={{ item }} state=present enablerepo="nginx"
   with_items: "{{ nginx_pkgs }}"
   when: nginx_is_el|bool and nginx_official_repo
 
-- name: Install the nginx packages
+- name: Install the nginx packages for all other distributions
   package: name={{ item }} state=present
   with_items: "{{ nginx_pkgs }}"
   environment: "{{ nginx_env }}"
-  when: not nginx_official_repo
+  when: not nginx_is_el|bool