Add sourcemap support for src/Task/Assets/Scss.php

[AronNovak]

Related issue

#884

Overview

This pull request:

• Adds a feature

Summary

By doing:

$compiler_options['sourceMap'] = Compiler::SOURCE_MAP_INLINE;
$result = $this->taskScss()
   ->setFormatter($formatter)
   ->compiler('scssphp', $compiler_options)
   ->run();

Description

It might need extra work for support sourcemap in a file.

(#885 against master)