Merge pull request #12 from vliedel/master

fixed various android bugs, use unsigned char
Merge pull request #13 from vliedel/master

fixed zeromq string port read + some android things
fixed string initialization
Merge branch 'master' of https://github.com/dobots/rur-builder into origin
fixed getting std::string where it should be string
added android heartbeat
zmq messages have no 0 at the end
nodejs ports now work with strings too
use utf8 and don't dereference a pointer that could be destroyed already