add utility functions

hostFromUrl, resourceFromUrl, toString added
toString needed because of gcc bug 52015
listeners and networkWorker added
add token class prototype
expand ServiceConfiguration
fix comment
partially implement token request
few minor fixes
listeners replaced by c++11 features
Service constructor signature fixed

added missing const modifier
Merge pull request #9 from swat32exe/partially-implement-token-request

Partially implement temporary credential request