support for pylint through ArcanistConfigurationDrivenLintEngine

since ArcanistConfigurationDrivenLintEngine->loadAvailableLinters() uses $linter->getLinterConfigurationName()
that method needs to exist in ArcanistPyLintLinter.php

adding these lines to .arcconfig
  "lint.engine": "ArcanistConfigurationDrivenLintEngine",
  "lint.pylint.codes.error":  "^[EF].*",
  "lint.pylint.codes.warning":  "^W.*",
  "lint.pylint.codes.advice":  "^[RC].*",
  "lint.pylint.rcfile": ".pylintrc"

and this to .arclint
    "pylint": {
      "type": "pylint",
      "include": "(\\.py$)"
    },

does the trick