Add source parameter for pecl provider

Add source pararameter to php::extension. It's allready in the pecl provider.
Configure extensions only after installing php-cli

Fixes #18.
Fix pecl provider with ensure => latest
Add hack for Debian to enable PHP extensions

As we use the mods-available directory for placing config files that
load PHP extensions, we need to activate loading these configs for cli
and fpm on Debian-based systems.

Fixes #17.
Prepare release 1.1.1
Merge branch '1.1.x'