fix deprecation warnings about calling scope() with a hash

DEPRECATION WARNING: Calling #scope or #default_scope with a hash is deprecated. Please use a lambda containing a scope. E.g. scope :red, -> { where(color: 'red') }. (called from included at ~/surveyor/lib/surveyor/models/answer_methods.rb:13)

We use instance_eval because we need the scope lambda to run in the
context of the including Class, not the Module in which the code is
defined.

lib/surveyor/models/answer_methods.rb

@@ -10,7 +10,7 @@ def self.included(base)
         base.send :has_many, :validations, :dependent => :destroy
 
         # Scopes
-        base.send :default_scope, :order => "#{base.quoted_table_name}.display_order ASC"
+        base.instance_eval {default_scope ->{order "#{base.quoted_table_name}.display_order ASC"}}
 
         # Mustache
         base.send :include, MustacheContext

lib/surveyor/models/question_methods.rb

@@ -12,7 +12,7 @@ def self.included(base)
         base.send :belongs_to, :correct_answer, :class_name => "Answer", :dependent => :destroy
 
         # Scopes
-        base.send :default_scope, :order => "#{base.quoted_table_name}.display_order ASC"
+        base.instance_eval {default_scope ->{order "#{base.quoted_table_name}.display_order ASC"}}
 
         # Mustache
         base.send :include, MustacheContext

lib/surveyor/models/survey_methods.rb

@@ -12,7 +12,7 @@ def self.included(base)
         base.send :has_many, :translations, :class_name => "SurveyTranslation"
 
         # Scopes
-        base.send :scope, :with_sections, {:include => :sections}
+        base.instance_eval {scope :with_sections, ->{includes :sections}}
 
         @@validations_already_included ||= nil
         unless @@validations_already_included

lib/surveyor/models/survey_section_methods.rb

@@ -7,7 +7,7 @@ def self.included(base)
         base.send :belongs_to, :survey
 
         # Scopes
-        base.send :scope, :with_includes, { :include => {:questions => [:answers, :question_group, {:dependency => :dependency_conditions}]}}
+        base.instance_eval {scope :with_includes, ->{ includes :questions => [:answers, :question_group, {:dependency => :dependency_conditions}]}}
 
         @@validations_already_included ||= nil
         unless @@validations_already_included