Manage configuration of extensions.

PHP can be compiled with `--with-config-file-scan-dir` which enable
adding all INI files from a given directory - configurable by
`hwr_path_php_mods_enabled` variable. You can get loaded ini files list
using `php_ini_scanned_files()` function.

Instead of controlling priority and making it a necessity (and a pattern
for file names) for extensions, the user should control the file names
which doesn't enforce a file name for him and also enables him using a
priority system.

The tasks to control configuration were moved to the PECL YML and an
option to remove all unmanaged configuration files is added.