Add new type definition for npm package toobusy-js.

• Use a meaningful title for the pull request. Include the name of the package modified.
• Test the change in your own code. (Compile and run.)
• Add or edit tests to reflect the change. (Run with npm test.)
• Follow the advice from the readme.
• Avoid common mistakes.
• Run npm run lint package-name (or tsc if no tslint.json is present).

Adding a new definition:

• The package does not already provide its own types, or cannot have its .d.ts files generated via --declaration
• If this is for an NPM package, match the name. If not, do not conflict with the name of an NPM package.
• Create it with dts-gen --dt, not by basing it on an existing project.
• tslint.json should be present, and tsconfig.json should have noImplicitAny, noImplicitThis, strictNullChecks, and strictFunctionTypes set to true.

Type defintion is based on: https://github.com/STRML/node-toobusy/blob/master/toobusy.js