Refactored options.
Unified option parameters.
Added ini file support.
Applied option priority of cli > ini > env.
Prepared google oauth to support the new options API.
Updated helios.go to support the new options API.
Updated google auth module to support ini config.
Renamed OptionParser to Config.
Renamed ProxyServer.OptionParser to ProxyServer.Config.
Cleaned up some codes in options.go for readability, doesn't impact performance/functionalities.
Fixed a typo in GetTopString.
Changed application parameter http-address to http.
Added check for upstream url, default to "/", fixed #1.
Merge pull request #2 from Tuxuri/development

Development