replace yajl and json gem with ffi-yajl
convert to using ffi_yajl
fix another Yajl reference
we can still emit JSON::ParserErrors in compat mode
remove commented lines
remove another comment
Merge pull request #1540 from opscode/lcg/ffi-yajl-gem

replace ruby-yajl with ffi-yajl gem
Bump ffi version since chef-dk depends on chef and dep-selector and dep-selector uses ~> 1.9.
Use FFI::LastError instead of GetLastError for ffi 1.9.x compatibility.
Fix windows specs.
Misc spec fixes for windows.