dropbox.com/s/njwr5uy9buhngrv/C2Zipper.zip
I made a quick C# utility to take a plugin/behavior directory and make a .c2addon file. It's a command-line tool that works with drag & drop (including multiple directories)
i.e. if your plugin is in
c:\myplugin
it makes c:\myplugin.c2addon
The tool verifies that info.xml and the "files" subdirectory exists before attempting to do the zip.
Notes:
This requires .NET 4.5 assemblies, so you need Windows 8, Visual Studio 2012, or some other way to get .NET 4.5
I have included the source, not a binary, since Visual Studio Express 2012 for desktop is free, and no one should run random .exe files from the net. :)