read path attribute directly instead of doing send(...)

[marshall-lee]

I think it will be more correct to get a path value from object through self[column_name] but not with send column_name. It's "faster" and it's more correct in the context of a library. Methods, even if they're automatically created by ActiveRecord, belong to user's classes, not to us so we should neither invoke them nor make any assumption that they're exist. We work with path attribute, not with path method.

It must be changed everywhere in code.

[fluorescent-net]

All tests pass with changes in this commit.