add a function to convert errata advisory string to the url of that errata
make a class of some methods implements interfaces in rpmkit.updateinfo.base.Base instead of functions, in rpmkit.updateinfo.yumwrapper
follow changes in test target module
fix a bug that cs is not initialized when fakeroot is False
just update the copyright header (simplified a lot)
remove an extra line
make a class of some methods implements interfaces in rpmkit.updateinfo.base.Base instead of functions, in rpmkit.updateinfo.yumbase