OAI PMH translator

[stakats]

arXiv.org's page data will be best scraped by hitting their OAI PMH service, easily accomplished through a URL switch. In the likely event that we encounter other sites using a similar interface, suggest creating a dedicated translator to parse the resulting XML. Can then call this translator from an arXiv.org translator, etc. Assigning this to myself (stakats) here since my name doesn't appear in the ticket entry drop-down.