Add a few small consistency tweaks in hack
Refactor the handling of static-related build flags

This is as discussed with @shykes on IRC
Rename all cases of "docker-init" to "dockerinit" for consistency
Add dynbinary and dyntest scripts for building/testing a separate static dockerinit binary

After a nice long brainstorming session with @shykes on IRC, we decided on using a SHA1 hash of dockerinit compiled into the dynamic docker binary to ensure that we always use the two in a perfect pair, and never mix and match.
Merge pull request #2217 from tianon/links-dynbinary

Added ability to create dynamic docker and static dockerinit through make scripts directly