adjust <server-environment> to conform to airbrake.io/airbrake_2_2.xsd
adjust Endpoint url
add Notify function which does not include stactrace
Merge branch 'master' of github.com:seako/airbrake-go

Conflicts:
	airbrake.go
typo
Merge pull request #1 from seako/master

fixed a bug where xml wouldn't pass Airbrake's validation