change tsb.create(string) to tsb.create(require(string))

[olegchir]

Fixes an error on OSX 10.11 + latest node / gulp-tsb.
There's no string-arg version of tsb.create anymore.

Example of the error before this fix:

➜  node-express-typescript git:(master) gulp build
{ file: undefined,
  start: undefined,
  length: undefined,
  messageText: 'Failed to parse file \'src/tsconfig.json\': text.charCodeAt is not a function.',
  category: 1,
  code: 5014 }
{ file: undefined,
  start: undefined,
  length: undefined,
  messageText: 'Failed to parse file \'tests/tsconfig.json\': text.charCodeAt is not a function.',
  category: 1,
  code: 5014 }
[20:26:08] Using gulpfile /Volumes/data/testapps/vscode-samples/node-express-typescript/gulpfile.js
[20:26:08] Starting 'build'...
[20:26:08] 'build' errored after 12 ms
[20:26:08] TypeError: Cannot read property 'on' of null
    at DestroyableTransform.Readable.pipe (/Volumes/data/testapps/vscode-samples/node-express-typescript/node_modules/gulp/node_modules/vinyl-fs/node_modules/through2/node_modules/readable-stream/lib/_stream_readable.js:516:7)
    at Gulp.<anonymous> (/Volumes/data/testapps/vscode-samples/node-express-typescript/gulpfile.js:65:10)
    at module.exports (/Volumes/data/testapps/vscode-samples/node-express-typescript/node_modules/gulp/node_modules/orchestrator/lib/runTask.js:34:7)
    at Gulp.Orchestrator._runTask (/Volumes/data/testapps/vscode-samples/node-express-typescript/node_modules/gulp/node_modules/orchestrator/index.js:273:3)
    at Gulp.Orchestrator._runStep (/Volumes/data/testapps/vscode-samples/node-express-typescript/node_modules/gulp/node_modules/orchestrator/index.js:214:10)
    at Gulp.Orchestrator.start (/Volumes/data/testapps/vscode-samples/node-express-typescript/node_modules/gulp/node_modules/orchestrator/index.js:134:8)
    at /usr/local/lib/node_modules/gulp/bin/gulp.js:129:20
    at nextTickCallbackWith0Args (node.js:420:9)
    at process._tickCallback (node.js:349:13)
    at Function.Module.runMain (module.js:443:11)

And after this fix:

➜  node-express-typescript git:(gulp-tsb-require) gulp build
[20:34:11] Using gulpfile /Volumes/data/git/vscode-samples/node-express-typescript/gulpfile.js
[20:34:11] Starting 'build'...
"/Volumes/data/git/vscode-samples/node-express-typescript/src/routes/index.ts(1,1): Cannot compile modules unless the '--module' flag is provided with a valid module type. Consider setting the 'module' compiler option in a 'tsconfig.json' file."
[20:34:12] Finished 'build' after 1.02 s