Provide a convenient way to get all results from a com.google.gcloud.Page

In cases when paging between different requests is not necessary (all results are consumed in the same request/thread) a common usage-pattern would be as such:

Page<V> page = .... get first page
while (page != null) {
  for (V v : page.values()) {
    ...do something...
  }
   page = page.nextPage();
}

or

Page<V> page = .... get first page
do {
  for (V v : page.values()) {
    ...do something...
  }
  page = page.nextPage();
} while (page != null);

To avoid this boilerplate code It would be nice to add to the Page class a method to return
an Iterator for all the results (and let that Iterator do the paging).

Some options:

(1) add a static method such as Page.iterateAll(page)
(2) an instance method such as page.allValues() or page.iterateAll() or page.fetchAll()

Any preference or other suggestions?

I would prefer an instance method. I would also not use allValues as we alredy have a values method that returns Iterable instead. My preference is iterateAll or simply iterator provided that we document what the method does.