Add striping to some channel settings values

This should help a bit dealing with user entry errors while configuring
channels. Regarding #783, 2 out of 3 channels which fail to resolve the IP
address of the domain have a whitespace at the start/end of the domain, which
makes the DNS query fail. Plus, we've had authentication errors in the past due
to extra whitespace in the username and password.

app/models/channel.rb

@@ -40,6 +40,10 @@ class Channel < ActiveRecord::Base
 
   broker_cached
 
+  def name=(value)
+    super(value.try(:strip))
+  end
+
   def config
     self[:config] ||= {}
   end

app/models/channels/sip.rb

@@ -18,12 +18,12 @@
 class Channels::Sip < Channel
   validate :server_username_uniqueness
 
-  config_accessor :username
-  config_accessor :password
-  config_accessor :domain
+  config_accessor :username, strip: true
+  config_accessor :password, strip: true
+  config_accessor :domain, strip: true
   config_accessor :direction
   config_accessor :register
-  config_accessor :number
+  config_accessor :number, strip: true
 
   def register?
     register == true || register == "1"

config/initializers/active_record.rb

@@ -19,6 +19,7 @@ class ActiveRecord::Base
   def self.config_accessor(*names)
     options = names.extract_options!
     default = options[:default]
+    strip = options[:strip]
 
     names.each do |name|
       self.config_attrs << name
@@ -31,6 +32,7 @@ def self.config_accessor(*names)
         respond_to?(:encrypted_config_will_change!) ? encrypted_config_will_change! : config_will_change!
 
         self.config ||= {}
+        value = value.try(:strip) if strip
         self.config[name.to_s] = value
 
         # this is needed so attr_encrypted encrypts the value correctly