This reviews the code and fixes up suggestions made by team for
the HTTP paths PR #789.

- Removed feature-flag (this is backwards-compatible, so I see
no value in adding the flag)
- There was a URL transform happening for calls proxied to the
back end, I changed this for the nil-transform - i.e. it does not
change anything in the URL
- Introduced variables to describe the regex indicies used in
the URL trimming.

Tested with Docker Swarm with a ruby-microservice, with
system calls and with function calls using the UI.

Signed-off-by: Alex Ellis (VMware) <alexellis2@gmail.com>