Wrap vars in with_items: statements

[psivesely]

The use of raw vars in Ansible with_items statements has been deprecated because
of it's ambiguity: is a a string or a var?! To help make ourselves compatible
with future Ansible verions and get rid of some of those pesky deprecation
warnings (#1427), we're appropriately wrapping them in handlebars. Helps resolve
#1427.

[psivesely]

Supercedes #1435. Do see the conversation in that issue because there is more related work in the branch it was based off that we would like to merge when #1146 is resolved.

[conorsch]

As I mentioned in #1435 (comment), these changes will need to be explicitly tested and confirmed working with:

• ansible==1.8.4 (via pip) in staging VMs
• ansible==1.7.2 (via apt) on Tails

If both environments honor the changes, we should be good for merge.

[conorsch]

Ironically, Ansible warns about the allegedly superfluous presence of the handlebar syntax in with_items loops when run under old versions:

 [WARNING]: It is unnecessary to use '{{' in loops, leave variables in loop
expressions bare.

My, how times changed. While you're right that eventually we'll need to solve this problem to tackle #1146, it's not truly necessary at present, and the Ansible output will generate deprecation warnings no matter what we do (until #1146 is resolved). Still, I'm inclined to merge here—just need to repeat tests on hardware Tails.

[psivesely]

Assigned @justintroutman @commandnotfound because they're going to each be doing practice installs. I figured they may as well test this PR out since they'll be working with the hardware. Talk to me before you install SD to the app/mon server, and I'll help you test this.

[conorsch]

In #1146 we've decided to push for upgrading Ansible to 2.x during the 0.4 release. Therefore we should merge this into develop and hammer out the config tests described in #1580 to make sure the playbooks respond intelligently to out-of-date versions of Ansible.

Waiting for #1563 to be closed out, to avoid complicating the backporting of 0.3.11 changes onto develop. I'll clean up any conflicts that arise in this branch as a result of the backport.

[conorsch]

#1563 is closed out, so this should be good for merge. Related tasks for Ansible-v2 conversion tracked in #1146.