Merge pull request #507 from hintjens/master

First draft of zgossip class
Merge pull request #508 from hintjens/master

Problem: does not build or pass on libzmq v2.2
Update VS import props to allow delinking by dependent projects.
Merge pull request #509 from evoskuil/master

Update VS import props to allow delinking by dependent projects.
Fix zgossip errors/warnings on MSVC and missing DLL exports.
Merge pull request #510 from evoskuil/master

Fix zgossip errors/warnings on MSVC and missing DLL exports.
MSVC - emit debug symbols into debug static/ltcg libs.
Merge pull request #511 from evoskuil/master

MSVC - emit debug symbols into debug static/ltcg libs.
Merge pull request #513 from hintjens/master

More changes for zgossip and other improvements
Feature: Added more syslog functionality to zlog
Merge pull request #515 from mvala/master

Feature: Added more syslog functionality to zlog
Switched to using zhash_first/next iterators for tuples

Much nicer...! I really like using this iterator style, keeping the
cursor context in the collection.
Adding service name for tracebilty
Revert "Feature: Added more syslog functionality to zlog"

This reverts commit b289d0622e7ce10cbcb5d6e9e13eb0bb6dc60119.

Mostly because complex constructors are an anti-pattern; it is
nicer to configure an object by setting properties on it. Also
because zlog was abstracted over syslog, and this change breaks
the abstraction and makes it specific to syslog.