Implemented Mikkelson, k66r from Axelrod's second.

[gaffney2010]

Fairly straightforward implementation. I changed the variable J2 to credit = 7-J2. It's chosen so that credit is a good thing, and I center it at 7, so that we cooperate when credit is positive.

Fingerprints:

[marcharper]

The failing test is due to one of the ensemble strategies:

FAIL: test_strategy (axelrod.tests.strategies.test_meta.TestMetaMajorityLongMemory)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/build/Axelrod-Python/Axelrod/axelrod/tests/strategies/test_meta.py", line 340, in test_strategy
    expected_actions=actions, seed=1)
  File "/home/travis/build/Axelrod-Python/Axelrod/axelrod/tests/strategies/test_player.py", line 521, in versus_test
    self.assertEqual(match.play(), expected_actions)
AssertionError: Lists differ: [(C, C), (C, D), (C, C), (C, D), (D, C)] != [(C, C), (C, D), (D, C), (C, D), (D, C)]
First differing element 2:
(C, C)
(D, C)
- [(C, C), (C, D), (C, C), (C, D), (D, C)]
?                      --------
+ [(C, C), (C, D), (D, C), (C, D), (D, C)]

[drvinceknight]

This all looks great to me: I have run the axelrod_fortran test suite locally and read through the strategies. Thanks @gaffney2010 👍