On Debian systems vhost definitions should go in sites-available and be
symlinked to from sites-enabled. apache2.conf should include
sites-enabled/*.conf. This updates the module to follow this behaviour.

Closes #161. Closes #135

In testing the sites-enabled symlinks, it was discovered that the
virtual_docroot parameter did not work on debian without also including
the vhost_alias httpd mod. This corrects that behaviour.

In testing sites-enabled behaviour, it was discovered that php loading
did not perform as expected on Debian due to including configuration
files from mods-available instead of mods-enabled. This corrects that
behaviour.

The ability to purge configs to preserve pristine working conditions is
often critical to avoid breaking apache unintentionally. On many
platforms the apache package will create directories into which other
apache mod package will place configs. These can conflict with configs
managed by puppet and cause apache service failures. This would normally
be corrected by purging those stray files on the second puppet run, but
in the mean time apache would have stopped. Single-run idempotency is
preferable.

Since Puppet cannot separately ensure => directory and purge => true,
this commit uses an exec resource and mkdir to create the directories,
and uses a file resource *after* all mods have been processed to do the
ownership & purging.

Sites symlinks

make fragment names unique to support multiple balancerclusters

resources don't refresh the service when the configs are updated, but they
should. (#230).

This commit fixes the issue by adding:

        notify  => Service['httpd'],

to all file resources.

Note that the modification has only been tested with a few of the modules.

add proxy_set option to balancer

Add severname parameter to httpd.conf

Issue 230 specifiy that: The apache::mod::* classes that have .conf file

People don't read:

    directory => [ { path => '/path/to/directory', <directive> => <value> } ],

as psuedo-code example instructing you on how to form an array of hashes, they
read them as puppet DSL examples that they can copy and paste into their
apache::vhost stanzas.

make directories examples real puppet DSL

Features:
- Add `servername` parameter to `apache` class
- Add `proxy_set` parameter to `apache::balancer` define

Bugfixes:
- Fix ordering for multiple `apache::balancer` clusters
- Fix symlinking for sites-available on Debian-based OSs
- Fix dependency ordering for recursive confdir management
- Fix `apache::mod::*` to notify the service on config change
- Documentation updates

Release 0.8.0