[all] require 'dm-core' if a dm constant is used
[all] require 'dm-core' if a dm constant is used

1) This is a workaround for current bundler which
   doesn't yet respect the order in which the gems
   have been declared in the Gemfile, when doing a
   Bundler.require

2) Actually I also think it's good style to require
   all the code that we need in order to perform
   a task. Even if most applications will always
   require dm-core before requiring any of its
   plugins, it still doesn't hurt to be explicit
   and to avoid possible bugs in the first place.

datamapper/dm-ferret-adapter