(TK-20) Refactor tests

Refactor tests, moving proxy-related tests and overriding tests
into their own files.
(TK-20) Add partial multi-route support

Add init function to core which supports multi-endpoint
configurations for a single service. Add multi-route support
to context handler service functions.
(TK-20) Implement multi-route support

Implement multi-route support to all handler service functions
for the webrouting service. Also, modify the APIs of all
handler service functions to accomodate this.