[FEATURE] replace request with superagent

sendPayment, buildPayment, getNotification
[TASK] update superagent version, npm test
[TEST] buildPayment
[TEST] ripple addresses fixtures
[TEST] send and confirm payment
[TEST] send payment
[TASK] delete unused methods/tests
[FEATURE] getPayments, replace request > superagent
[TASK] add timeout flag to npm test
[TEST] get/setTrustLines, notifications, updateAcctSettings
[TASK] rename to _
[FEATURE] generateUUID, generateNewWallet
[TEST] generate new wallet
Merge pull request #14 from stevenzeiler/superagent

LGTM