Fixed tests so that they will still run without failure when dependencies (PyCrypto, ecdsa) are missing. (Tests are skipped if libraries are not present.)
Fixed tests so that they will still run without failure when
dependencies (PyCrypto, ecdsa) are missing. (Tests are skipped if
libraries are not present.)

rainierwolfcastle/pyjwt,mark-adams/pyjwt,Wolfium/pyjwt,jpadilla/pyjwt,jmgamboa/pyjwt,mindw/pyjwt,progrium/pyjwt