Use single-quotes to contain SSH keys as they may contain double-quotes

Fixes #1624.

docsite/rst/playbooks2.rst

@@ -402,7 +402,7 @@ This syntax will remain in future versions, though we will also will provide way
 is an example using the authorized_key module, which requires the actual text of the SSH key as a parameter::
 
     tasks:
-        - authorized_key name=$item key="$FILE('/keys/$user1')"
+        - authorized_key name=$item key='$FILE(/keys/$item)'
           with_items:
              - pinky
              - brain

library/authorized_key

@@ -49,7 +49,7 @@ options:
 examples:
    - code: 'authorized_key: user=charlie key="ssh-dss ASDF1234L+8BTwaRYr/rycsBF1D8e5pTxEsXHQs4iq+mZdyWqlW++L6pMiam1A8yweP+rKtgjK2httVS6GigVsuWWfOd7/sdWippefq74nppVUELHPKkaIOjJNN1zUHFoL/YMwAAAEBALnAsQN10TNGsRDe5arBsW8cTOjqLyYBcIqgPYTZW8zENErFxt7ij3fW3Jh/sCpnmy8rkS7FyK8ULX0PEy/2yDx8/5rXgMIICbRH/XaBy9Ud5bRBFVkEDu/r+rXP33wFPHjWjwvHAtfci1NRBAudQI/98DbcGQw5HmE89CjgZRo5ktkC5yu/8agEPocVjdHyZr7PaHfxZGUDGKtGRL2QzRYukCmWo1cZbMBHcI5FzImvTHS9/8B3SATjXMPgbfBuEeBwuBK5EjL+CtHY5bWs9kmYjmeo0KfUMH8hY4MAXDoKhQ7DhBPIrcjS5jPtoGxIREZjba67r6/P2XKXaCZH6Fc= charlie@example.org 2011-01-17"'
      description: "Example from Ansible Playbooks"
-   - code: "authorized_key: user=charlie key=$FILE(/home/charlie/.ssh/id_rsa.pub)"
+   - code: "authorized_key: user=charlie key='$FILE(/home/charlie/.ssh/id_rsa.pub)'"
      description: "Shorthand available in Ansible 0.8 and later"
 author: Brad Olson
 '''