Case insensitive search of method names

https://bugzilla.redhat.com/show_bug.cgi?id=1134500

When searching for methods the case shouldn't be taken into account
so the sql that comes out of here will be: `lower(name) = ?`.
This will no hit an index on `name`. If we care, then we can do something like `create_index :miq_ae_method, "lower(name)"`