debian packaging issues

[dohnto]

In #6 @rembish introduced several issues with debian packaging.

• Some go packages didn't download automatically.
• GOPATH doesn't set at all.
• lintian isn't happy:

E: goenvtemplator changes: bad-distribution-in-changes-file Seznam
W: goenvtemplator source: diff-contains-git-control-dir .git
E: goenvtemplator source: source-is-missing goenvtemplator2
E: goenvtemplator source: source-is-missing debian/goenvtemplator/usr/bin/goenvtemplator
W: goenvtemplator source: changelog-should-mention-nmu
W: goenvtemplator source: source-nmu-has-incorrect-version-number 2.0.0~rc2
W: goenvtemplator source: no-debian-copyright
W: goenvtemplator2: hardening-no-relro usr/bin/goenvtemplator2
E: goenvtemplator2: no-copyright-file