Consider dot files whitelisting

[voxik]

Currently, the generated files sections for backports gem contains following dot files:

%exclude %{gem_instdir}/.gitignore
%{gem_instdir}/.gitmodules
%exclude %{gem_instdir}/.irbrc
%exclude %{gem_instdir}/.travis.yml
%doc %{gem_instdir}/.document

As you can see, there are some "unknown" dot files left. Shouldn't we use whitelist instead? E.g.:

%exclude %{gem_instdir}/.*

would exclude all dot file. If there is some know whitelisted dot file which should be preserved, we could do later:

%{gem_instdir}/.whitelisted

Unfortunately I am not sure if this is supported by RPM. Anyway, if all dot files are removed from the package at the end, they should be replaced by wildcard exclude to save some lines.