typescriptPreprocessor.options not correctly parsed

[cwalv]

The readme suggests specifying compiler options similar to tsconfig.json:

typescriptPreprocessor: {
      // options passed to the typescript compiler
      options: {
        sourceMap: false, // (optional) Generates corresponding .map file.
        target: 'ES5', // (optional) Specify ECMAScript target version: 'ES3' (default), or 'ES5'
        module: 'amd', // (optional) Specify module code generation: 'commonjs' or 'amd'
        noImplicitAny: true, // (optional) Warn on expressions and declarations with an implied 'any' type.
        noResolve: true, // (optional) Skip resolution and preprocessing.
        removeComments: true, // (optional) Do not emit comments to output.
        concatenateOutput: false // (optional) Concatenate and emit output to single file. By default true if module option is omited, otherwise false.
      },

but the results are passed unparsed to ts.transpile. As in #22, the module option will be ignored unless it matches one of the integer values from ts.ModuleKind. To match the tsconfig.json behavior, we'd have to parse the config.