Rewrote the installation process, added 1.7.4 support

This installation rewrite job-ifies most units of installation logic, and
then I add jobs for installing resources.  This adds support for the new
resources system, as well as the major layout changes added in 1.7.3

Additionally, support was added for new auth responses which are then
piped into the launch code for Minecraft.
Fixed an issue which caused version.json to be set before downlodaing
mods.
Make sure to set up directories before attempting to retrieve current
version.
Merge pull request #3 from TechnicPack/master

Merge with upstream