Issue #36 - add another example of raven-go package usage
fix travis build
Issue #37 - make examples part of the golang documentation
fix tests
Issue #37 - applied changes according to the comments

- nil instead of map[string]string{}
- generate trace instead of calling undefined trace() func
- var req *http.Request
- use %q for error message in fmt.Sprintf
Issue #37 - drop ExamplePacket and leave example with NewPacket
Issue #37 - remove os and errors packages import
Merge pull request #37 from OShalakhin/master

add another example of raven-go package usage