Fix deprecation warnings in inline templates

The puppet-swift modules emit deprecation warnings of the form:

Warning: Variable access via 'pipeline' is deprecated. Use
  '@pipeline' instead. template[inline]:2
   (at (erb):2:in `result')

These are due to missing @ signs in inline ERB templates in
storage/server.pp and proxy.pp.  This patch fixes them.

Change-Id: I3745cfd86c4332f00bc10a0999088691b3833147
Closes-Bug: #1282717