Docs reorganisation

[drvinceknight]

#536

Main:

• Relabelling of tutorial sections and some corresponding reorganisation.
• Landing page with 3 code snippets showing Matches, Tournaments and Moran processes.
• Initial tutorials are now: installation, building a match and then tournament. This replaces the current getting started section: http://axelrod.readthedocs.org/en/latest/tutorials/getting_started/getting_started.html which had installation and a tournament. I don't think this is necessary given the landing page.

Minor:

• Removing the ecological example from prob end.
• Adding an example to the new tournament docs.
• Minor rst syntax fixing and new images (boxplots replaced with violon plots as matplotlib now can handle violon for some of the ones that had boxplots kicking in).
• Changing strategies -> players in various parts (this is clearer, a strategy instance is a player)

[marcharper]

Very nice :) Thanks for taking care of this!