Fix errors with webpack and @motorcycle/loader on Windows

[Frikki]

ERROR in ./src/bootstrap.ts
Module build failed: TypeError: Cannot read property 'kind' of undefined
    at Object.isSourceFile (C:\**\node_modules\@motorcycle\compiler\node_modules\typescript\lib\typescript.js:11101:21)
    at Object.printNode (C:\**\node_modules\@motorcycle\compiler\node_modules\typescript\lib\typescript.js:66817:40)
    at Object.compile (C:\**\node_modules\@motorcycle\compiler\lib\compile.js:43:30)
    at Object.loader (C:\**\node_modules\@motorcycle\loader\lib\index.js:10:29)
 @ multi (webpack)-dev-server/client?http://localhost:8080 ./src/bootstrap.ts