Clean-up to enforce consistent Puppet code style

* If not interpolating variables, prefer single to double quotes.
* Distinguish arrays from resources by adding space inside the square brackets.
* Omit path where possible. (May be an anti-pattern -- Otto doesn't like it --
  but looks cleaner and hasn't gotten me into trouble yet.)
* Prefer 'present' / 'absent' as ensure values over resource-type-specific
  variants like 'installed' or 'file'.
* Use spaces rather than underscores or hyphens to separate words in resource
  titles.

Change-Id: I920e155ba10bcfc10dc74464f15dba5ca32c25bb