Deleting EasyHandle,MultiHandle and libcurlHelpers from URLSession/http

Moved lib curl specific code [libcurlHelpers.swift,EasyHandle.swift and MultiHandle.swift] from URLSession/http to URLSession/libcurl
libcurl abstractions like EasyHandle and MultiHandle are not specific to HTTP.Hence moved out of the HTTP folder to a common licurl folder

Author: saiHemak