Added support for arrays in php ini configuration

Currently arrays are merged to a string for php-ini configuration in the hieradata yaml file:

Example configuration:
```YAML
php:
    ini:
        display_errors: On
        error_reporting: '-1'
        extension:
            - 'mongo.so'
            - 'zmq.so'
```

The current template will concatenate the values and create a php ini configuration like this:
```BASH
[CUSTOM]
error_reporting=-1
display_errors=true
extension=mongo.sozmq.zo
```

This new template will interpret the array and create a config like this:
```BASH
[CUSTOM]
error_reporting=-1
display_errors=true
[CUSTOM_1]
extension=zmq.so
[CUSTOM_0]
extension=mongo.so
```