Fix --force-handlers, and allow it in plays and ansible.cfg

The --force-handlers command line argument was not correctly running
handlers on hosts which had tasks that later failed. This corrects that,
and also allows you to specify force_handlers in ansible.cfg or in a
play.

test/integration/test_force_handlers.yml

@@ -0,0 +1,28 @@
+---
+
+- name: test force handlers (default)
+  tags: normal
+  hosts: testgroup
+  gather_facts: False
+  connection: local
+  roles:
+  - { role: test_force_handlers }
+
+- name: test force handlers (set to true)
+  tags: force_true_in_play
+  hosts: testgroup
+  gather_facts: False
+  connection: local
+  force_handlers: True
+  roles:
+  - { role: test_force_handlers }
+
+
+- name: test force handlers (set to false)
+  tags: force_false_in_play
+  hosts: testgroup
+  gather_facts: False
+  connection: local
+  force_handlers: False
+  roles:
+  - { role: test_force_handlers }