Allow empty shas if in soft mode.
Drop 1.8.7 support rather than hacking spec results.
Merge pull request #10 from jdutil/empty_shas

Allow empty shas if in soft mode.
Merge pull request #12 from jdutil/remove_support

Drop 1.8.7 support rather than hacking spec results.
Prefix rather than suffix original and sha methods.
Update spec text.