Fix for off by one errors in link generation

Based on the tests, links are generated from page 0 to page N.

If there are 5 entries, and pages have 2 elements, the last page should be 2.
If there are 21 entries, and pages have 100 elements the last page should be 0.

I think the tests were not OK, which is why the implementation failed. The offending test case is:

```JS
describe('when there is not a next page and last page is not complete', function(){
  before(function () {
    this.result = linker.createLinks({
      per_page: 100,
      total: 21,
      page: 0
    });
  });

  it('should not return a link to the next page', function () {
    this.result.should.not.have.property('next');
  });
});
```