It seems that there is a bug in libzmq 4.2.0 cmake configs that prevents
linking to it without installing.
Solution: disable libzmq 4.2.0 for cmake builds
libzmq build with default settings now which build all the tests and
performance tools. This is not required for cppzmq build and slows down
it only.
Solution: disable tests build for libzmq and make it release only.
* Added overload constructor (c++11 only) taking iteratable object.
It would be easier to use std::string, std::array etc to construct
a message now. Making it a draft for now in case it is too greedy
and needs to be more specialize.
* Added equal and not euqal operator to message_t as a recommended
and expected way of comparing objects in C++.
* deprecated C style equal method as operator== should be used instead
(point above).
* Added message_t test covering all available message_t's constructors
