add invoice create and invoice pay.
Updated the README to include .recipients and .transfers API information
Added recipient and transfer functionality
Fixed missing data parameter in recipients.update
Added Balance API
Uncaptured property deprecated on Stripe API as of 2.9.12 https://stripe.com/docs/upgrades  Removed from test suite.
Merge branch 'master' into add-invoice-create-and-pay
add test
Merge pull request #49 from emilioTe/master

Implements 'Sending Transfers'
Fix some transfer/recipient requests
Merge pull request #52 from devongovett/master

Fix some transfer/recipient requests
Add new invoice functions to README.
Merge pull request #1 from willwhite/add-invoice-create-and-pay

Add new invoice functions to README.
Merge pull request #51 from pchw/add-invoice-create-and-pay

Implements 'Create an invoice' and 'Pay an invoice'
4-space to 2-space tabs, double quotes to single quotes.
Partial not-working refactor
More non-working
New structure. Charges working in new style.
Clean up various docs
Validate ID and add Customers