update + add software defns for testing

need to be able to pull unreleased artifacts from git to test.
libyajl2 gem needs to install first
fix flags and rake prep libyajl2-gem
remove libyajl2 gem

the git submodule makes this not work
Revert "remove libyajl2 gem"

This reverts commit 4ac21ac5f960b659aee8b37489791478a371c6d8.
need this for testing

pushing a broken libyajl2-gem breaks omnibus, so we need to be able to
build and test off a git branch, and need to use the git submodule
commands.
Merge pull request #310 from opscode/lcg/ffi-yajl-testing

update + add software defns for testing