Increase `express-annotations` coverage to 100%

Here's a lot more tests that cover the `express-annotations` API and catch every single possible use of `app.findAll`.

I also switched the testing style to the BDD `expect`-style that we had in all of the other Modown tests, and I used more realistic use-cases in my tests instead of `/foo` and `/bar`.

Coverage is as follows:
```
  Express Annotations
    ✓ should extend the Express app with extra methods 
    ✓ should return the app as is if the brand is already there 
    #annotate
      ✓ should return the app instance when called 
      ✓ should only accept route paths as strings 
      ✓ should annotate a path correctly with an annotations object 
      ✓ should extend existing annotations on the route 
      ✓ should create an empty annotations object on the route if none are passed in 
    #findAll
      With invalid routes
        ✓ should return an empty object if no routes were set up with annotations 
        ✓ should return an empty object if we have no string-based routes 
      With valid routes
        ✓ should accept a string and return all routes with that given annotation property 
        ✓ should accept an object and return all routes with those annotation key/value pairs 
        ✓ should accept an array of annotations and return all matching routes 
        ✓ should accept a variable number of arguments as annotation filters 
        ✓ should accept a function and return all matching routes 
        ✓ should return an empty object for an unmatched filter 
        ✓ should match routes between different HTTP methods 
        ✓ should contain the correct information inside each route 

  17 tests complete (22 ms)

=============================== Coverage summary ===============================
Statements   : 100% ( 46/46 )
Branches     : 100% ( 24/24 )
Functions    : 100% ( 10/10 )
Lines        : 100% ( 43/43 )
================================================================================
```