Define a total order for Action

[jsafyan]

This enables sorting Actions for Axelrod-Python/axelrod-dojo#50.

[marcharper]

This is the failing test:

======================================================================
ERROR: test_sequence_player (axelrod.tests.strategies.test_sequence_player.TestSequencePlayer)
Basic test for SequencePlayer.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/build/Axelrod-Python/Axelrod/axelrod/tests/strategies/test_sequence_player.py", line 27, in test_sequence_player
    self.assertEqual(C, player.strategy(opponent))
  File "/home/travis/build/Axelrod-Python/Axelrod/axelrod/strategies/sequence_player.py", line 40, in strategy
    return self.meta_strategy(s)
  File "/home/travis/build/Axelrod-Python/Axelrod/axelrod/strategies/sequence_player.py", line 32, in meta_strategy
    if value == 0:
  File "/home/travis/build/Axelrod-Python/Axelrod/axelrod/action.py", line 35, in __eq__
    return self.value == other.value
AttributeError: 'int' object has no attribute 'value'

Otherwise LGTM

[drvinceknight]

Looks good, thank you @jsafyan! 👍 👍