return last resolved model if `{conditional: true}`

[ralphsmith80]

It looks like this commit left out the return statement here. Since we're close to a release I'm not fixing this yet. Additionally this is a performance measure to not send a request when it is unneeded. Here are some things to consider when we do fix this;

• what if we include params with the conditional that would require a reload. For example.

model.refresh({include: ['accesslist']}, {conditional: true})

put on the breaks

We're not going to get crazy with this stuff trying to resolve special case logic here. If a special call is made with params the require a reload then just don't include the conditional option.