Feature phpcs xml and pathfix

[benallfree]

This PR fixes 3 things:

1. Integrates PR Search for phpcs.xml file in workspace root folder #29

2. Fixes a bug where phpcbf.standard was not resolving paths correctly

3. Fixes Does Nothing! #21. Exec path needs to be set to the project root so it can correctly search for installed_paths via phpcs --config-set installed_paths <path/to/custom/coding/standard>

[dossy]

What's the reason for the temporary file? If this VSCode extension just operated on the PHP file in-place, the phpcbf script automatically looks for and navigates up parent directories looking for a series of phpcs.xml-like filenames and uses the first one it finds ... the whole temp file thing breaks this very elegant mechanism.