Fix version condition for Active Admin >= 1.0
Fix version condition for Active Admin >= 1.0

A regular expressions is used to check whether to use the new
`ActiveAdmin::ResourceDSL`. This regular expression did not support
active admin version > 0.9.

Now it uses `ActiveAdmin::ResourceDSL` by default and uses the old code
for versions that match /^0\.[1-4]/.

velaluqa/activeadmin-cancan,velaluqa/activeadmin-cancan,velaluqa/activeadmin-cancan