Support array syntax inside plugins

Added

• You can now use array syntax ([]) for defining JSON arrays in plugin configuration. For example, in addition to something like this:

  plugin `myCoolPlugin#v2`, {
    features 'foo', 'bar'
  }

  You can also now write it equivalently like this:

  plugin `myCoolPlugin#v2`, {
    features ['foo', 'bar']
  }

  This just improves the overall consistency of the DSL.