Add Aaron Viviano to AUTHORS.

Prevent test failures on 2.x build.

Update libzmq version to 2.2.0.

Add prerelease support to package script.

Script also includes libzmq-version.txt, which contains the version of
libzmq packaged with the assembly.

Merge branch 'master' into 2.2

Issue #39: Set correct lib output path in nuspec.

Move output assemblies up one level to the 'lib' folder from 'lib/net20'.
This indicates to NuGet that the assemblies can be used in alternate
project types, such as Silverlight.

Add scripts for creating NuGet packages.

* Sign clrzmq and clrzmq-ext assemblies
* Set default version to 0.0.0.0 to indicate Development