[FEATURE] add paging to GET /balances
[DOC] update documentation for payments API endpoints
[FEATURE] add paging to GET /trustlines
Merge pull request #205 from boxbag/account-lines-paging

[FEATURE] add paging to GET /trustlines and GET /balances
[TEST] refactor payments test
Merge pull request #207 from boxbag/payments-test

[TEST] refactor payments test
Add database test
Merge pull request #208 from ripple/tests

Add database test
[TASK] rename fee endpoint to `/transaction-fee`