Avoid displaying the YSOD for file not found.

- For FileNotFoundException and DirectoryNotFoundException, display a
  nicer-looking 404 page.

Fixes #1.
Added 'Welcome Page' to the title bar.

Fixes #7.
Better-looking 500 page.
Forgot to add the error pages to the output.
*Stop* including views in the output directory.
Remove .PDB files from the included web app.