[feature] add pprof functionality to allow better analysis of Sherpa

[jrasell]

Is your feature request related to a problem? Please describe.
Currently only the sherpa runtime metrics and log messages can provide insights into the Sherpa server performance. It would be beneficial to have a method which allows better insights into the Sherpa server performance and behaviour.

Describe the solution you'd like.
It would be ideal to have an option to enable pprof for visualization and analysis of a running Sherpa server. This will help identify bottlenecks or edge cases as well as help optimize the server.

stdlib link - https://golang.org/pkg/net/http/pprof/
Google Github link - https://github.com/google/pprof