Various App-scripts stability issues

[danbucholtz]

I am working on verifying/fixing the following things. Some work already (probably anyway), some don't. Once I do these, I will release 0.0.37 with webpack support.

1. Handle deleting sass files/folders while serving
2. Handle adding sass files/folders whilee serving
3. Start serve with broken sass
4. Verify sass continues working if I intentionally break it and then fix it.
5. Handle copying when a src file doesn't exist
6. Handle adding Typescript files/folders while serving
7. Start serve with broken Typescript file, fix it, and observe the build not working correctly.

Thanks,
Dan