build: rename swarm deb package to ethereum-swarm; change swarm deb version from 1.8.x to 0.3.x (#16988)

* build: add support for different package and binary names

* build: bump up copyright date

* build: change default PackageName to empty string

* build, internal, swarm: enhance build/release process

* build: hack ethereum-swarm as a "depends" in deb package

* build/ci: remove redundant variables

* build, cmd, mobile, params, swarm: remove VERSION file; rename Version to VersionMeta;

* internal: remove VERSION() method which reads VERSION file

* build: fix VersionFilePath to Version

* Makefile: remove clean_go_build_cache.sh until it works

* Makefile: revert removal of clean_go_build_cache.sh

build/deb/ethereum/deb.copyright

@@ -0,0 +1,14 @@
+Copyright 2018 The go-ethereum Authors
+
+go-ethereum 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.
+
+go-ethereum 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 go-ethereum. If not, see <http://www.gnu.org/licenses/>.