DMP Queue pallet (#416)

* Introduce the converter into the hub

* Parachain recognises Rococo governance body as admin

* Whitespace

* Use UsingComponents for fee payment in XCM

* Fixes

* Fixes for XCM permissions

* Remove encode_call test

* Fixes

* Rococo Collator supports Shell runtime

* Fixes

* Fixes

* Initial draft of DMP Queue pallet

* DMP Queue builds.

* Companion for Polkadot gav-allow-xcm-exec

* Bump

* Fix std

* Fixes

* fix and improve docs

* fix compile errors in tests

* add test for try_service_message

* update cargo.lock

* Fixes

* Make test name read well

* Fixes

* Add a couple of simple tests

* Tests

* Tests

* Update pallets/dmp-queue/src/lib.rs

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

* Update pallets/dmp-queue/src/lib.rs

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

* Update pallets/dmp-queue/src/lib.rs

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

* Update pallets/dmp-queue/src/lib.rs

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

* Update pallets/dmp-queue/src/lib.rs

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

* Update pallets/dmp-queue/src/lib.rs

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

* Update pallets/dmp-queue/src/lib.rs

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

* Chain ID and ParaID don't collide

* Fixes

* Update pallets/dmp-queue/src/lib.rs

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

* Update pallets/dmp-queue/src/lib.rs

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

* Fixes

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>
Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>