[atlas] Measurement creation tools and library

Hi, I'm announcing a set of Python-based command-line tools/library for measurement creation available at https://github.com/USC-NSL/ripe-atlas. Since the focus is heavily on assisting measurement creation, I think that it should compliment Sagan nicely. It has been slowly under development for a while now but still has plenty of room to grow in supporting all of the options for different measurement types. Thanks, Matt