Integration tests

[radu-matei]

We should have automated tests that run all applications based on the templates.

[itowlson]

Also various test cases of applications that have built beyond the templates:

• A local app that uses asset files
  • Should check that assets are correct, and that files not specified as assets are not accidentally made available
• A bindle app that uses modules and assets stored in parcels
• An app that outputs headers and environment variables (could be combined with the asset cases)
  • Multiple overlapping routes to make sure prioritisation is stable and relative pathing is correct (may be able to do this via unit tests but if so need to be sure it is end to end)