Updates phpcs config in defaults.yml

[byrond]

• Fixes --ignore flag for phpcs is documented in defaults.yml but not used by default in build.xml #157 by updating the comments to reference the new extensions config.
• Removes the deprecated ignore config.

[byrond]

Fooey! I actually found that I needed the --ignore option for a module that will include a vendor and node_modules directory. I'm going to rework this to add the option back in and use it in build.xml.

[byrond]

Never mind! I can just move my code-review step earlier in the build, so there are no vendor and node_modules directories to be scanned.

[byrond]

Argh. I think I'm switching sides again and saying we could use this. Moving the code-review step works for CircleCI, but during development, if your module has Composer or Node dependencies, they will need to be ignored.

[becw]

Another option here would be to provide a default phpcs.xml file, and remove all of the customized phpcs config and commands from the-build. That way, the build.xml file could run phpcs without arguments, developers could easily run the same phpcs config by running phpcs directly, and it would be more obvious that phpcs was set up for a project...

[becw]

I merged #185 instead.