Working mod_authnz_ldap support on Debian/Ubuntu

Remove the `authnz_ldap` key from $mod_packages in `apache::params` so
an installation of the non-existent package `libapache2-mod-authz-ldap`
is not attempted.

Properly manage the `authnz_ldap.conf` file template and set the
`LDAPVerifyServerCert` directive according to $verifyServerCert
in `apache::mod::authnz_ldap`.

Also update spec tests accordingly.

This fixes only the superficial problems in issue #494. Better support
for mod_ldap and mod_authnz_ldap is required, as discussed there.
Merge pull request #496 from antaflos/fix_debuntu_mod_authnz_ldap

Working mod_authnz_ldap support on Debian/Ubuntu
Add support for overriding ErrorDocument

add support for overriding ErrorDocument settings in both, vhost and
directory context.
With documentation and tests included this fixes #474
Merge pull request #498 from igalic/error_document

Add support for overriding ErrorDocument
Remove eronous duplication of ForceType

c42c41d introduced a sloppy copy/paste error in the _directories.erb
template. This removes it, thus fixing #500
Merge pull request #501 from igalic/dedup-forcetype

Remove eronous duplication of ForceType
No implicit <Directory> entry for ScriptAlias path

Support for ScriptAlias currently implicitly and automatically creates
<Directory> configuration directives for the path component in a given
ScriptAlias directive. These are not useful or needed, according to the
mod_alias documentation. Fixes issue #486.

This change also indirectly relates to #487 because the implicitly
created <Directory> entry for each ScriptAlias path also had
`SSLOptions +StdEnvVars` set for that directory.
Merge pull request #488 from antaflos/no_directory_for_scriptalias

No implicit <Directory> entry for ScriptAlias path
Add support for ScriptAliasMatch directives

Much like in PR #483 extend the _scriptalias.rb template so that the
`scriptalias` parameter in `apache::vhost` can contain `aliasmatch`
hashes which get translated to `ScriptAliasMatch` directives. Fixes
issue #480.

Includes basic spec tests and updated documentation in README.md.

Note again that puppet-rspec silently drops `$1` when specifying test
values so we match `FOO` instead of `$1`. From a simple spec test
perspective there shouldn't be a difference and this is better than
having no tests at all.
Merge pull request #502 from antaflos/support_scriptaliasmatch

Add support for ScriptAliasMatch directives