Conver the More Context section into a History section

A history section that provides context :) around the origin and progression of VVV from an internal 10up project to a community organization.
Add an initial CONTRIBUTING document
Move milestones and labels down
Update CHANGELOG with current 1.1 list
Update recommended versions for Vagrant and VirtualBox
Add a link to contributing guidelines in README
Make all contributors links HTTPS

It's like you could tell when GitHub started defaulting to https for everything. Or it's like I typed everything manually before? I don't get it.
Tweak section on WordPress and Vagrant mailing list
Merge pull request #283 from Varying-Vagrant-Vagrants/housekeeping

[PR] Update README, Add initial CONTRIBUTING document