Adds specs for template contents

Both conditional and plain content are tested. All template-related
pending tests have been addressed, one in spec/compute_spec.rb that
was tied to a cookbook_file resource has been just removed.

Change-Id: Ib2d8871794920a10ad8e111fc89ab03ab057d3dc
Partial-Bug: #1182563
Merge "Adds specs for template contents"