[fedora-java] fixes in new guidelines

[Michal Srb]

Hello guys,

I made few corrections in java packaging guildelines draft as decided at 
the java-sig meeting yesterday.

Draft: https://fedoraproject.org/wiki/User:Msrb/JavaPackagingDraft
Diff: 
https://fedoraproject.org/w/index.php?title=User%3AMsrb%2FJavaPackagingDraft&diff=324725&oldid=323304

a quick summary:
- fixed fedora versions in Maven section
- clarify a bit why BR on java-devel is optional in Maven packages

Let me know if you think something is still missing or should be fixed.

Thanks

Michal Srb