Clean-ups

It would have been better to split this up into atomic commits, but I didn't,
and now it'd be too much work to split up.

* Simplified remote URL specification for Git.
* Deleted Chromium module; unused.
* Removed /etc/profile.d/puppet-managed in favor of managing /etc/profile.d
  directly.
* Removed 'var' parameter from env::var; it now always gets the var name from
  the resource title.
* Qualified paths to some exec resources.
* Renamed 'check_service_freshness' to 'isfresh'.
* Made ackrc configuration global, by provisioning /etc/ackrc instead of
  ~/.ackrc.

Change-Id: Ib00295e434fafc78f8ab6c79bc2bbffb6193b17f
Add apache::def from operations/puppet

env.d/ is a bit much, in hindsight. It's hard to imagine this facility being
useful for anything other than defining a runtime parameter, which
operation/puppet's apache::def does better.

Since that apache::def depends on PuppetLabs's stdlib module, I took the code
from PS1 of Ifdd6d2a66 (which did not rely on it) instead.

Change-Id: I754253c412767aceeed7caf4d377a0202fbf56d5