Add "team head to head" support
Add team events support

Useful for generating detailed stats on teams. From the PA docs,
"Returns all matches and their events for a particular team in a
specific competition season or for all competitions between two
dates."
Add team results endpoint
Add seasonId to the competitions results

The format returned by PA has chanegd since this endpoint was created
and the seasonId is important to some other calls.
Add squad endpoint
Add endpoint to fetch teams in a given competition
Generalise Head2Head and add player head to head support
Add player appearance endpoint
Add player stats and player profiles
Add team stats summary

Generalise stats summary so it can apply to teams and players.
Add backwards compatitbility fix for the Season change
Merge remote-tracking branch 'origin/master' into additional-endpoints
Add README examples for new endpoints
Merge pull request #24 from guardian/additional-endpoints

Additional endpoints