Add custom_fragment parameter

The parameters are often limited in what they can express. this allows
custom templates to be used for the configuration
Merge pull request #89 from hunner/add_config

Add custom_fragment parameter
Reduce template code duplication

The listen template is essentially just a combination of
frontend/backends in haproxy, and lots of code was duplicated between
the three templates. This commit moves the stanzas into fragments.
Merge pull request #91 from hunner/fragment_templates

Reduce template code duplication
Define each server/port combination on its own line

When referencing
http://cbonte.github.io/haproxy-dconv/configuration-1.4.html#5 and
http://cbonte.github.io/haproxy-dconv/configuration-1.4.html#server it
does not appear that having multiple address/port combinations on one
line is officially supported, and indeed the "check" option only applies
to the first port, not later ones.

This commit breaks each server into its own line.
Merge pull request #93 from hunner/fix_backend_port

Define each server/port combination on its own line
Add bind_options for frontends

Bind options are available for listen resources, but not for frontend
services, but they should be.

Closes #64
Merge pull request #94 from hunner/bind_options

Add bind_options for frontends