Rename skip_migrate to skip_migrations

This should fix pages fails on MySQL.

I suspect, "skip_migrate" is not the right option name, "skip_migration" is also used to skip the seeds in: https://github.com/refinery/refinerycms/blob/10e63784613682db8f8b094878f60a01413b39f6/core/lib/generators/refinery/cms/cms_generator.rb#L269

Author: bricesanchez

core/lib/generators/refinery/dummy/dummy_generator.rb

@@ -34,7 +34,7 @@ def generate_test_dummy
       opts[:skip_action_cable] = true
       opts[:skip_action_mailer] = true
       opts[:skip_keeps] = true
-      opts[:skip_migrate] = true
+      opts[:skip_migrations] = true
       opts[:template] = refinery_path.join("templates", "refinery", "edge.rb").to_s
 
       invoke Rails::Generators::AppGenerator,