Fixes #1327 -- adds multifernet
Added docs for multifernet
improved the error message
Handle non-iterable arguments reasonable
flake8 + cleanup
Merge branch 'master' into multi-fernet
added docs stuff on when added
Merge pull request #1422 from alex/multi-fernet

Fixes #1327 -- adds multifernet
add load_dsa_parameter_numbers on multibackend
Added a utility for implementing a read only property of another field
oops, fix recursion
Merge pull request #1425 from reaperhulk/fix-missing-method

add load_dsa_parameter_numbers on multibackend
Merge pull request #1426 from alex/read-only-property

Added a utility for implementing a read only property of another field
Merge branch 'master' into verify-interfaces

Conflicts:
	cryptography/utils.py
Statically verify interface implementations, and fix all the resulting bugs