Rpm version fix - revert using `rpm` for parsing

JFYI: the dependency problem may look like this:

```
rpm --specfile --qf "%{VERSION}" yast2-storage.spec
chyba: line 122: Illegal char in: Requires:	libstorage-devel = balíček libstorage-devel není nainstalován
chyba: dotaz na spec soubor yast2-storage.spec selhal, nemohu parsovat
```

Although running in `C` locale helps, it seems that `rpm` does too much work and the simple `grep` and `sed` seems to be a better approach...