Extract humanize method from Extlib::Inflection to CouchRest.humanize, so that Extlib::Inflection dependency can be removed

lib/couchrest/validation/validation_errors.rb

@@ -60,7 +60,7 @@ module CouchRest
       cattr_writer :default_error_messages
 
       def self.default_error_message(key, field, *values)
-        field = Extlib::Inflection.humanize(field)
+        field = CouchRest.humanize(field)
         @@default_error_messages[key] % [field, *values].flatten
       end
 

lib/couchrest/validation/validators/format_validator.rb

@@ -64,7 +64,7 @@ module CouchRest
 
         error_message = @options[:message] || ValidationErrors.default_error_message(:invalid, field_name)
 
-        field = Extlib::Inflection.humanize(field_name)
+        field = CouchRest.humanize(field_name)
         error_message = error_message.call(field, value) if error_message.respond_to?(:call)
 
         add_error(target, error_message, field_name)

lib/couchrest/validation/validators/length_validator.rb

@@ -54,7 +54,7 @@ module CouchRest
 
         # XXX: HACK seems hacky to do this on every validation, probably should
         #      do this elsewhere?
-        field = Extlib::Inflection.humanize(field_name)
+        field = CouchRest.humanize(field_name)
         min = @range ? @range.min : @min
         max = @range ? @range.max : @max
         equal = @equal