v0.14.0

• Updated some out-of-date dependencies
• Update documentation to explicitly set fees
• Add Server.prototype.fetchBaseFee, which devs can use to fetch the current
  base fee; we plan to add more functions to help suggest fees in future
  releases
• Add includeFailed to OperationCallBuilder for including failed
  transactions in calls
• Add operationFeeStats to Server for the new fee stats endpoint