Go agent v1.10

New

• Added new RecordCustomMetric method to Application. This functionality can be used to track averages or counters without using custom events. See Custom Metric Documentation
• Fixed import needed for logrus. The import Sirupsen/logrus had been renamed to sirupsen/logrus. Thanks to @alfred-landrum for spotting this.
• Added ErrorAttributer, an optional interface that can be implemented by errors provided to Transaction.NoticeError to attach additional attributes. These attributes are subject to attribute configuration.
• Added Error, a type that allows direct control of error fields.
• Updated license to address scope of usage.