pass max to spider. more logging in spider

- read from open file
introduce —-follow to specify links
make urls into relative urls
revamp max number of pages to visit.

raise error only when visited that many pages.
this allows us to set the limit to 1 and test out the waters

(since it is cached, we can continue where we left off)
general rules about links

- don’t allow links to span multiple sites
- multi-site param (not sure if I want to remove)
- whitelist of path extensions to visit

- spider_spec#meta_fu to use urls
- spider#visit only supports a single string
- introduce cli#option_hash (kinda like splice)
- trim spider#log