Move path and link_name related functions and regex patterns to a new soc/logic/path_linkname.py module, and fix all dependencies. path/link_name functionality is becoming the generic way to identify entities in the Datastore in a URL-compatible way.

# Directions for web crawlers.
# See http://www.robotstxt.org/wc/norobots.html.

User-agent: HTTrack
User-agent: puf
User-agent: MSIECrawler
User-agent: Nutch
Disallow: /