Consolidate README links
More README changes
Added charge_customer_at
Updated the specs *grumble*grumble*grumble*
Merge pull request #30 from gocardless/charge_customer_at

Added charge_customer_at
Merge branch 'master' into Crowdcube_master

# By Grey Baker (2) and Kit (2)
# Via Grey Baker (1) and Kit (1)
* master:
  Updated the specs *grumble*grumble*grumble*
  Added charge_customer_at
  More README changes
  Consolidate README links