Don't pass validators' public keys with attestations (#186)

* Don't pass validators' public keys with attestations

* Update statement-table's Misbehaviour typedef

* Update network/router

* Expand MessageValidationData

* Try to fix tests

* Extend ApiContext

* Remove 'index_mapping' from the SessionParams

* Construct index_mapping from authorities

* Move index_mapping to TableContext

* Add test for index_mapping order