Modifies the behavior of an update so that it can create an object if it
was new. This allows an "upsert"-like functionality where the SDK will
tend to do the right/expected thing.
This is a tad janky in that it checks for the existence of a class-level
`.create` method which is expected to come from a different module, but
most modules in the project are already fairly deeply intertwined and
co-dependent.
Fixes#165.
Rationale:
Sometime you don't care about the current state of a resource
you just want to update one of it's attributes.
It should only require one request.
fixes#52
```ruby
c = Stripe::Customer.new("cus_1EqKjPaFs4ZwDD")
c.description = 'Ny new Description'
c.save
```
Before:
```json
{
error: {
type: "invalid_request_error",
message: "A parameter provided in the URL (id) was repeated as a GET or POST parameter. You can only provide this information as a portion of the URL.",
param: "id",
}
}
```
After:
Successfully update the customer and return it's whole state.
