Release mode.

[Amar Takhar]

I've added a release mode to the build.  The instructions are in the commit 
message.  This lowers the barrier for entry for using NTPSec and ensures our 
tested versions work the same for the public.

I'll be enabling snapshots using BuildBot and uploading them to ftp.ntpsec.org 
for users that want the version that passed testing.  The snapshot will only be 
created if all builds / tests pass.

I didn't want this in the latest release as I wanted to catch any edge cases 
through regular development.

This also means we can remove the 'waf' binary from the Git repository and 
package it in with the tarball releases in the future.


Amar.