Fixed some major bugs with implications, cleaning up the cache

expiration process and adding some additional tests.

Cleaned up the unit tests.  They should all run cleanly with rake
test:units now.

test/factories/tag_alias.rb

@@ -1,4 +1,2 @@
 Factory.define(:tag_alias) do |f|
-  f.creator {|x| x.association(:user)}
-  f.creator_ip_addr "127.0.0.1"
 end

test/factories/tag_implication.rb

@@ -1,4 +1,2 @@
 Factory.define(:tag_implication) do |f|
-  f.creator {|x| x.association(:user)}
-  f.creator_ip_addr "127.0.0.1"
 end

test/factories/wiki_page.rb

@@ -2,6 +2,4 @@ Factory.define(:wiki_page) do |f|
   f.creator {|x| x.association(:user)}
   f.title {|x| Faker::Lorem.words}
   f.body {Faker::Lorem.sentences}
-  f.updater_id {|x| x.creator_id}
-  f.updater_ip_addr "127.0.0.1"
 end