Say something if the template engine isn't available for theme

fixes #600
Fix :num_pages options to keep backwards-compatible
Using old ruby hash syntax
Restore backwards compatibility of #num_pages in #paginate

Conflicts:
	lib/kaminari/helpers/action_view_extension.rb
Use class method '.themes' in ViewGenerator#copy_or_fetch
Only generate template files when doing rails g kaminari:views ...

This basically reverts 12822c9ee127664896d52ba5713d7c0c8f47794d.

closes #623.
DataMapper 1.2 still needs Rails 3.2...
Fix the test suite for mongoid 40

It didn't run due to:

  moped-2.0.2/lib/moped/cluster.rb:254:in `with_primary':
    Could not connect to a primary node for replica set #<Moped::Cluster @seeds=[<Moped::Node resolved_address="127.0.1.1:27017">]>
    (Moped::Errors::ConnectionFailure)
Fix mongo mapper test suite

https://travis-ci.org/amatsuda/kaminari/jobs/41827391#L98