Added greedy pattern matching when validating attribute separators

[jlaamanen]

Fixes #149 by making token pattern matching greedy. Otherwise, if an attribute named foo appears before another attribute named foo-bar, the latter attribute would be matched as foo, making the -bar part look like a separator after foo token.

Also fixed unit tests that were failing because invalid.pug was no longer invalid.

[ezhlobo]

@pugjs/linter hey, is there a chance we can merge this and publish?