[BioRuby] Remove class name aliases: Bio::DDBJ, Bio::RefSeq

[Naohisa Goto]

Hi all,

I'd like to remove the following classes that are only aliases of other classes.
I've heard that the existance of these classes with empty contents is a
source of confusion for newcomers. Moreover, I think such aliases make
things complicated and may make refactoring difficult. I also think
these might be waste of namespace.

* Bio::DDBJ, Bio::RefSeq (Same as Bio::GenBank)

In the upcoming release, I'm planning to show warning messages when
using the classes. Then they will really be removed in the future release.

-- 
Naohisa Goto
ngoto at gen-info.osaka-u.ac.jp / ng at bioruby.org