Clean problem with migration scripts

I've noticed that we have two migration scripts with prefix 001 and schema-revision with value 1. 
Migration script 001_rename_disk_mode_attribute.rb was already included in 001_aaa_from_pebbles.rb, that's way we can remove this bit. 
I renamed also 001_aaa_from_pebbles.rb to 001_migration_from_pebbles.rb, which is more reasonable name.
that looks wrong to me btw. it should probably be 

`ruby
a['disk_mode'] = a['disk-mode'] || ta['disk_mode']
`