Backend import priority

[RazerM]

python-jose/jose/backends/__init__.py

Lines 2 to 8 in cc710e0

	try:
	from jose.backends.pycrypto_backend import RSAKey # noqa: F401
	except ImportError:
	try:
	from jose.backends.cryptography_backend import CryptographyRSAKey as RSAKey # noqa: F401
	except ImportError:
	from jose.backends.rsa_backend import RSAKey # noqa: F401

pycrypto and cryptography should swap places here for the case where both are installed.

[RazerM]

Oops I only searched issues, but there's already a PR #122

[zejn]

Merged #122