WIP: add onNewReconnectMessage and improve test coverage

[kpetku]

This improves upon #25 by adding an interval that can be shortened for tests. Feel free to reject and/or improve upon this if this approach is too messy.

[coveralls]

Coverage increased (+1.04%) to 98.137% when pulling 12ee4dd on kpetku:master into a137208 on gempir:ping.

[coveralls]

Coverage increased (+1.04%) to 98.137% when pulling 12ee4dd on kpetku:master into a137208 on gempir:ping.

[coveralls]

Coverage increased (+1.04%) to 98.137% when pulling 12ee4dd on kpetku:master into a137208 on gempir:ping.

[coveralls]

Coverage increased (+2.9%) to 100.0% when pulling 5050be0 on kpetku:master into a137208 on gempir:ping.

[gempir]

Thank you. You're approach is clean and readable. I'll update the Go versions since 1.6 shouldn't be supported anyway anymore.