enum support

[matozoid]

It seems that enums aren't supported. They look like this:

{ id: 'Language',
type: 'string',
enum: [ 'en', 'nl' ],
enumDescriptions: [ '', '' ] }

And cause this:

............/gapidts/lib/api/schema.js:7
throw new Error("unknown type: " + base.type);
^

Error: unknown type: string
at new Schema (.........../gapidts/lib/api/schema.js:7:19)
at .........../gapidts/lib/api/root.js:11:20
at Array.map (native)
at new Root (.........../gapidts/lib/api/root.js:10:61)
at Object.emit (.........../gapidts/lib/emitter.js:14:16)
at gapidts (.........../gapidts/lib/index.js:14:21)
at processFromSource (.........../gapidts/lib/cli.js:108:18)
at Object. (.........../gapidts/lib/cli.js:30:5)
at Module._compile (module.js:456:26)
at Object.Module._extensions..js (module.js:474:10)

And thanks for the work :)