Yosemite build alternative fix.

This commit should fix the build for Yosemite OS, which was broken
due to the introduction of conflicting macros.

PR #77 fix the build.
This should also fix the build, but in a less intrusive way.

It prevents the definition of the htonll and ntohll function
inside the zmqpp namespace if a equivalent macro is present.
message.cpp has been update so that it will either call the macro
or the zmqpp function.

However, it is yet to be tested on Yosemite.
Merge pull request #78 from xaqq/yosemite-fix

Yosemite build alternative fix.
Create zap_request.hpp

Initial Implementation ZMQPP security.
Create zap_request.cpp

Initial Implementation ZMQPP security.
Create auth.hpp

Initial implementation ZMQPP security.
Create auth.cpp

Initial implementation ZMQPP security.
Create test_auth.cpp

Initial implementation ZMQPP security.
Added support for CURVE security examples

Added libsodium reference
The Grasslands Pattern

The Classic ZeroMQ model, plain text with no protection at all.
The Strawhouse Pattern.

We allow or deny clients according to their IP address. It may keep spammers and idiots away, but won't stop a real attacker for more than a heartbeat.
The Woodhouse Pattern

It may keep some malicious people out but all it takes is a bit of network sniffing, and they'll be able to fake their way in.
The Stonehouse Pattern

Where we allow any clients to connect, but we promise clients that we are who we claim to be, and our conversations won't be tampered with or modified, or spied on.
The Ironhouse Pattern

Security doesn't get any stronger than this. An attacker is going to have to break into your systems to see data before/after encryption.
The Ironhouse2 Pattern

Security doesn't get any stronger than this. An attacker is going to have to break into your systems to see data before/after encryption.
 
 This is exactly the same example but broken into two threads so you can better see what client and server do, separately.
Update AUTHORS
Added ZMQPP security
Added support for CURVE security
Update auth.hpp
Update zap_request.hpp
Travis build error fix.