jormungandr: Error handling in stat_manger for RabbitMQ

When rabbitMQ is re-initialized and jormungandr is running,
jormungandr cannot push stat masage to rabbitMQ even if
the connection exists.

If it happens the connection will have to be re-initialized.
jormungandr: Error handling modified after comments

If error of type connection or channel,
reinitialize the connection and if success
Push the stat message.
jormungandr: Error handling in stat_manager corrected.

Message modified
Previous connection released.
Merge pull request #388 from kadhikari/NAVITIAII-918

jormungandr: Error handling in stat_manger for RabbitMQ