Backport all v0.6 changes to master... (#552)

* Bump Substrate and versions (#531)

* Bump versions

* Build fix.

* Enable governance (#536)

* Enable governance

* Tweak a few parameters

* Bump substrate, versions. (#538)

* Bump substrate, versions.

* Build fix

* Bump rpc deps (#537)

* Update to latest sub

* Revert branch update

* Update.

* Update tests.

* Ignore warnings in tests.

* Revert substrate (#540)

* Version bump

* Bump Substrate, versions. (#542)

* Bump Substrate, versions.

Also revert the enabling of democracy

* Build fix

* Bump Substrate (#544)

* Bump Substrate

* Fix

* A few tidyups

* Bump Substrate (#547)

* Bump Substrate

* Another bump

* Fixed build for new block_import API

* Enable grandpa migration. (#549)

* Enable grandpa migration.

* Bump runtime version