Merge pull request #16 from joseramonc/master

update generator default migration
Merge branch 'rails-3.x' of github.com:joseramonc/adminpanel into rails-3.x
add rails 4 support
Merge branch 'master' of github.com:joseramonc/adminpanel
display_attributes can be independent of index or show
Merge branch 'rails-3.x' of github.com:joseramonc/adminpanel
rails 4 migration