Update postfix element per install instructions.

Updates postfix element to reload instead of restart. This is called
for in the installation instructions. This also fixes a issue with
the postfix element where the current restart can fail and cause ORC
post-install scripts with higher numbers to not run.

Change-Id: I853a2f2890fcc0b006fcfc214fb1ca900d03613a
Authored-by: Chris Krelle <nobodycam@gmail.com>