Merge pull request #686 from hintjens/master

Added test case for issue 566
Merge pull request #687 from hintjens/master

Updated CMake project for test_issue_566
Add '-lssp' linker flag for Solaris. Check for libraries after host specific setup.
Disable compiler warning for Solaris
Merge pull request #688 from mattconnolly/master

This pull requests fixes building on SmartOS and possibly other Solaris-like systems
declare z85_encode / decode in zmq_utils

they are used by curve_keygen, but not available
include missing platform.hpp in curve_keygen

it was excluded, so HAVE_SODIUM would never be defined,
leading to curve_keygen always reporting "recompile with libsodium"
Merge pull request #689 from minrk/curve_keygen

include missing platform.hpp in curve_keygen
config for libsodium in alternate path, using CPP flags for both C and C++ sources.
Merge pull request #690 from mattconnolly/master

config for libsodium in alternate path, using CPP flags for both C and C...
add zmq_curve_keypair to zmq_utils
use zmq_curve_keypair in curve_keygen
return NULL and set EINVAL on bad z85 input

asserts aren't appropriate for checking user input.
Merge pull request #691 from minrk/curve_keygen

Expose zmq_curve_keypair via zmq_utils
Packaging for zmq_curve_keypair function

* Added new man page for this
* Added test case, in tests/test_security_curve.cpp
* Noted in zmq_utils.h that these methods are documented