Updated `omnibus` with `*.metadata.json` fixes

The latest version of Omnibus contains important fixes for the generated
metadata files. In particular the following items are fixed:

* `*.metadata.json` files are properly copied over to $PWD/pkg at build
completion on Windows builders: opscode/omnibus-ruby@f90842baf6
* Latest version of Ohai properly retrieves platform and platform
version on Windows builders: opscode/omnibus-ruby@bfedf87e6a
* Build iteration has been added to `*.metadata.json` for use in
publishing tasks: opscode/omnibus-ruby@3dfd9b3773
Updated `omnibus-software` for compat with latest `omnibus`
Update references to Omnibus "build project"

A couple documentation cleanups related to 7ed605.
Merge pull request #194 from opscode/schisamo/updated-omnibus

Updated `omnibus` with `*.metadata.json` fixes
Update omnibus to pull in updated `ffi-yajl` and `libyajl2`
Merge pull request #197 from opscode/schisamo/install-fix

Update omnibus to pull in updated `ffi-yajl` and `libyajl2`
remove ffi-yajl software dep

we're just going to pull from the chef.gemspec now
Merge pull request #198 from opscode/lcg/gem-install-ffi-yajl

remove ffi-yajl software dep
bump omnibus-ruby/software + ffi-yajl deps
[TESTING] Update to the latest Omnibus