Set up initial draft

[maxachis]

This adds two bits of functionality in support of #566:

• An offset for getting URLs, so a user can get either the next URL, or the nth next URL, depending on what they have for their offset
• The ability to disable retrieving the next URL after posting annotations -- this is so we don't unnecessarily load redundant information.

[josh-chamberlain]

@maxachis thanks for getting started on this! Before we merge into dev, it would be good to know which of the ideas from the issue are being implemented, so we can pare the remainder off into a future issue.