Remove signHash in favor of unsafe_sign_hash

[kclowes]

What was wrong?

It's not safe to sign random hashes, but occasionally developers want to do so. We were undecided about what to do with the method, but decided to add a new method called unsafe_sign_hash and finally remove signHash

Closes #85

How was it fixed?

Removed signHash, moved functionality to unsafe_sign_hash.

LMK if you think we should add more/different docs

Todo:

• [x] Clean up commit history

• [x] Add or update documentation related to these changes

• [x] Add entry to the release notes

Cute Animal Picture

[Uxio0]

Sounds like a really good solution, thanks @kclowes