Fixed drush version detection for Drush 7.

Drush 7 changed the default "--pipe" output format of drush core-status
to JSON. Added "--format=list" and "--strict=0" to silence errors on
drush versions not knowing about the "--format" option.
Fixed documentation.

Don't pretend to be flymake-phpcs.
Mark `drupal/flymake-phpcs-standard' as obsolete.

And as an alias for `drupal/phpcs-standard'.
Merge branch 'develop' into pr/35
Drupal 8 moved the version number to a new file.

Fixes #36.
Added .cask to .gitignore.
No need for make-local-variable.
No need for #.
Properly add our checkers to flycheck-checkers instead of enforcing it.
Really no need to check for existence of phpcs command.
Check for drupal/flycheck-phpcs-js-and-css in predicate, now we don't enforce it.