Add key manager basic API docstrings.
Add basic openpgp key handling to Key Manager
Make the key wrapper map an object property.
Make keymanager OpenPGP wrapper store using Soledad.
Add send_keys() and refresh_keys() to Key Manager.
Refactor, fixes, add api, tests.

* Change KeyTypeWrapper to EncryptionScheme
* Change OpenPGPWrapper to OpenPGPScheme
* Add missing and standardized crypto API.
* Add delete_key()
* Fix put_key raw so it puts either public or private keys.
* Fix gpg's is_encrypted()
* Fix openpgp's safe callbacks so they return correctly.
* Remove binascii because it generates invalid doc ids.
* Add tests.
Add key refreshing for KeyManager.
Use 'requests' module in KeyManager.
Remove gpg reference on Soledad usage.
Remove string conversion for encryption/decryption results.
return None if no key found, avoid KeyError
Various fixes
Add tests for key management remote methods.
Merge remote-tracking branch 'drebs/feature/key-manager' into develop