Add declaration of void Config::addSubscribe(string,string,string*)

Declaration of void Config::addSubscribe(string name,string type,string * value)
is missing in ofxSpacebrew.cpp, causing link error in VS2012
Merge pull request #8 from musiko/patch-1

Add declaration of void Config::addSubscribe(string,string,string*)
Merge remote-tracking branch 'origin' into feature-binary