Attribute Error initializing in latest versions

[FoamyGuy]

#134 changed the type of error that was caught. But it seems now the library fails it's initialization.

code.py output:
Traceback (most recent call last):
  File "code.py", line 25, in <module>
  File "/lib/adafruit_wiznet5k/adafruit_wiznet5k.py", line 246, in __init__
  File "/lib/adafruit_wiznet5k/adafruit_wiznet5k.py", line 390, in mac_address
AttributeError: 'tuple' object has no attribute 'split'

Code done running.

[FoamyGuy]

resolved by #125