Rename rococo-collator to polkadot-collator (#435)

* Rename `rococo-collator` to `polkadot-collator`

Also contains some other small changes.

* Test fixes and some further search&replace

cumulus/polkadot-parachains/src/main.rs

@@ -0,0 +1,30 @@
+// Copyright 2019-2021 Parity Technologies (UK) Ltd.
+// This file is part of Cumulus.
+
+// Cumulus is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Cumulus is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Cumulus.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Cumulus test parachain collator
+
+#![warn(missing_docs)]
+#![warn(unused_extern_crates)]
+
+mod chain_spec;
+#[macro_use]
+mod service;
+mod cli;
+mod command;
+
+fn main() -> sc_cli::Result<()> {
+	command::run()
+}