Refactor local build process.
Hide Drupal-specific code or move it to the Drupal toolstack.
Blacklist certain files from being symlinked while building Drupal.
Merge branch 'refactor-build' into mine

Conflicts:
	src/Command/EnvironmentListCommand.php
	src/Command/ProjectDrushAliasesCommand.php
	src/Command/ProjectGetCommand.php