Add test for cookies that match subdomains
Add test for cookies that match subdomains

A test to go with commit dae2733: Tests that when writing a cookies.txt
file:

* Cookies that only match exactly the domain specified must not have a
  leading dot, and must have FALSE as the second field.
* Cookies that match subdomains must have a leading dot, and must have
  TRUE as the second field.

bugmelody/mechanize,gchan/mechanize,jeremiahmarks/mechanize,jeremiahmarks/mechanize,sjchakrav/mechanize,eligoenergy/mechanize,eligoenergy/mechanize,uksa/mechanize,pwnall/mechanize,sjchakrav/mechanize,flavorjones/mechanize,pwnall/mechanize,sparklemotion/mechanize,sparklemotion/mechanize,uksa/mechanize,bugmelody/mechanize,gchan/mechanize