begin refactor of SandboxResource

properly test SandboxResource.create
fix SandboxResource#commit
remove accessor from Client that are overriding delegators
fix no method errors when saving and finding cookbooks
refactor uploading of SandboxResources to SandboxUploader

fix uploading of sandboxes after breaking changes in previous commits
fix broken sandbox resource acceptance test
Merge pull request #56 from reset/fix-sandboxes

Fix sandboxes