Support php_admin_(flag|value)s

Add support for php_admin_flags and php_admin_values to both
<VirtualHost> and directory context. Basic documentation & tests
for both cases included.

This Fixes #463
Fix $ports_file reference in Namevirtualhost.

This define was pointing at the params::ports_file version of the
variable, rather than the one defined in the main class, making it
impossible to correctly override.
Fix $ports_file reference in apache::listen.

This was pointing at ::params::ports_file instead of the main class,
causing relocation of the ports file to fail.
Merge pull request #532 from apenney/quick-fix

Fix $ports_file reference in Namevirtualhost.
Merge pull request #481 from igalic/php_admin

Support php_admin_(flag|value)s
update CONTRIBUTING with information about beaker

beaker has replaced our rspec-system tests. These new tests are run
differently. Before messing with our Rakefile, a good start is to just
document it.
Merge pull request #533 from igalic/contributing-beaker

update CONTRIBUTING with information about beaker
Support environment variable control for CustomLog
Merge pull request #527 from chieping/add-access-log-option

Support environment variable control for CustomLog
Fix rspec-puppet deprecation warnings

This commit changes all the spec tests to use contain_class
instead of include_class which is deprecated.
Merge pull request #534 from blkperl/spec_dep_warns

Fix rspec-puppet deprecation warnings