Support optional route constraints in MVC

This PR
1. Adds tests for inline constraint
2. Fixes tests broken by Routing change for inline constraints

The way inline constraints website is written, it uses configuration to read the templates. However this is not a pattern that we follow in our other functional tests. (The reason why it was done was to have the template be part of the test code rather than the website. )
Now might be a good time to reconsider that decision and follow one consistent pattern. 
Lets discuss it in person and get an agreement on this. 
@yishaigalatzer @rynowak