Fixes for FreeBSD get_memory_facts
Fixes for FreeBSD get_memory_facts

- swapinfo on FreeBSD 6 (maybe 7 too?) doesn't support the "-m" flag for
  fetching amounts in megabytes. This patch fetches amounts in kilobytes
  and divides by 1024 (and also returns the result as an int instead of
  a string).

- When no swap is configured, swapinfo prints a header line and nothing
  else:

    $ swapinfo
    Device         1K-blocks     Used    Avail Capacity

  The old version unexpectedly parsed that header line and emitted
  nonsense values like:

    "ansible_swapfree_mb": "Avail"
    "ansible_swaptotal_mb": "1K-blocks"

  This version emits those items altogether.

thaim/ansible,thaim/ansible