Reformat current release notes layout

This changes the layout of the release notes (Starting from the current
_.next_ version) to display something like the following (rendered
mockup):

  * Fixed bug which would cause major disturbance in the cosmos
    Symptoms are typically manifest in hallucinogenic experiences of
    functioning software
    * PRIORITY: PPPPP
    * ISSUES: BBBB

Rather than

* PRIORITY: PPPP

  Fixed bug which would cause major disturbance in the cosmos
  Symptoms are typically manifest in hallucinogenic experiences of
  functioning software

  ISSUES: BBB

Specifically, the new format allows us to save on whitespace between the
different sections, which is incredibly helpful when the bug description
itself is a line or two.

Change-Id: Ie5582bcdd864874e2fba1eb3cd43fb59e335c574
Reviewed-on: http://review.couchbase.org/40191
Reviewed-by: Brett Lawson <brett19@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>