[DRE-maint] Bug#702415: use anonscm.d.o url instead of git.d.o for VCS fields

[Praveen A]

package: gem2deb
version: 0.3.0
severity: minor

Currently lintian complains about the generated VCS field. Once the
field is changed to anoscm url, lintian is happy.

I: ruby-rack-piwik source: vcs-field-not-canonical
git://git.debian.org/pkg-ruby-extras/ruby-rack-piwik.git
git://anonscm.debian.org/pkg-ruby-extras/ruby-rack-piwik.git
N:
N:    The VCS-* field contains an uncanonical URI. Please update to use the
N:    current canonical URI instead. This reduces the network bandwidth used
N:    and makes debcheckout work independent of the port forwarding and
N:    redirections properly working.
N:
N:    Severity: minor, Certainty: possible
N:
N:    Check: fields, Type: binary, udeb, source
N: