api: make IP addresses in the API.

Make the following fields visible in API responses:

* ip_bans.ip_addr
* ip_geolocations.ip_addr
* ip_geolocations.network
* users.last_ip_addr (mod only)
* user_sessions.ip_addr
* api_keys.last_ip_address
* api_keys.permitted_ip_addresses

Before IP addresses were globally hidden in API responses because IPs were
present in a lot of tables and we didn't want to accidentally leak them.
Now that we've gotten rid of IPs from most tables, it's safe to unhide them.

app/logical/danbooru/ip_address.rb

@@ -6,11 +6,11 @@
 module Danbooru
   class IpAddress
     attr_reader :ip_address
-    delegate :ipv4?, :ipv6?, :loopback?, :link_local?, :unique_local?, :private?, :to_string, :prefix, :multicast?, :unspecified?, to: :ip_address
+    delegate :ipv4?, :ipv6?, :loopback?, :link_local?, :unique_local?, :private?, :to_string, :network, :prefix, :multicast?, :unspecified?, to: :ip_address
     delegate :ip_info, :is_proxy?, to: :ip_lookup
 
     def initialize(string)
-      @ip_address = ::IPAddress.parse(string.to_s)
+      @ip_address = ::IPAddress.parse(string.to_s.strip)
     end
 
     def ip_lookup
@@ -39,9 +39,13 @@ module Danbooru
       ip_address.include?(other.ip_address)
     end
 
+    def as_json
+      to_s
+    end
+
     # "1.2.3.4/24" if the address is a subnet, "1.2.3.4" otherwise.
     def to_s
-      ip_address.size > 1 ? ip_address.to_string : ip_address.to_s
+      ip_address.size > 1 ? "#{network}/#{prefix}" : ip_address.to_s
     end
 
     def inspect

app/logical/ip_address_type.rb

@@ -18,6 +18,8 @@ class IpAddressType < ActiveRecord::ConnectionAdapters::PostgreSQL::OID::Inet
   def cast(value)
     return nil if value.blank?
     super(Danbooru::IpAddress.new(value))
+  rescue ArgumentError
+    nil
   end
 
   # Serialize a Danbooru::IpAddress to a String for the database.