Update README.md to include Mac instructions

Added the steps to the best of my recollection.
Blog post for ruby 2 / sprint 15 appliances.
added link to blog archives
base archive # on blog's per-page pagination settings
fixed blog archive width
added style to the blog archive link
Merge pull request #179 from mfeifer/readme

Update README.md to include Mac instructions
Merge pull request #181 from jrafanie/ruby_2_appliance_post

Blog post for ruby 2 / sprint 15 appliances.
adding new submodule
adding new submodule
additional style & layout changes — also tags are sort/uniq'd
don't extend container for post-meta
Merge pull request #182 from ManageIQ/blog-fixups

Blog fixups
Merge branch 'master' into depot-WIP

Conflicts:
	.gitmodules
support images with a relative path in subrepos