roles/taiga: Deploy Taiga project management app

The *taiga* role installs the three components of Taiga:

* taiga-back
* taiga-events
* taiga-front

*taiga-back* is a Python application. Its dependencies are installed via
`pip` in the *taiga* user's site-packages, and the application itself is
installed by unpacking the archive. *taiga-events* is a Node.js
application. Its dependencies are installed by `npm`, and is itself
installed by unpacking the archive. Finally, *taiga-front* is a
single-page browser application that is installed by unpacking the
archive, and served by Apache.

Taiga requires PostgreSQL and RabbitMQ.

roles/taiga/tasks/taiga-events.yml

@@ -0,0 +1,52 @@
+- name: ensure nodejs is installed
+  package:
+    name:
+    - nodejs
+    - npm
+    state: present
+  tags:
+  - install
+
+- name: ensure taiga-events directory exists
+  file:
+    path: /usr/local/lib/taiga/taiga-events
+    owner: taiga
+    group: taiga
+    mode: '0755'
+    state: directory
+- name: ensure taiga-events is installed
+  become: true
+  become_user: taiga
+  unarchive:
+    src: '{{ taiga_events_url }}'
+    dest: /usr/local/lib/taiga/
+    remote_src: true
+
+- name: ensure taiga-events dependencies are installed
+  become: true
+  become_user: taiga
+  npm:
+    path: /usr/local/lib/taiga/taiga-events
+
+- name: ensure taiga-events is configured
+  template:
+    src: taiga-events.config.json.j2
+    dest: /usr/local/lib/taiga/taiga-events/config.json
+    owner: root
+    group: taiga
+    mode: '0750'
+  notify:
+  - restart taiga-events
+
+- name: ensure taiga-events systemd unit is installed
+  copy:
+    src: taiga-events.service
+    dest: /etc/systemd/system/taiga-events.service
+    mode: '0644'
+  notify:
+  - reload systemd
+  - restart taiga-events
+- name: ensure taiga-events starts at boot
+  service:
+    name: taiga-events
+    enabled: yes