style: if ! changed by unless

- if ! changed by unless as it is more readable
- !object.blank? is equivalent to object.present?, also more readable

app/models/conference.rb

@@ -551,7 +551,7 @@ class Conference < ActiveRecord::Base
         result[state.name] = count
       end
 
-      if !conference.events_per_week
+      unless conference.events_per_week
         conference.events_per_week = {}
       end
 
@@ -692,7 +692,7 @@ class Conference < ActiveRecord::Base
     events_per_week.each do |week, values|
       values.each do |state, value|
         if [:confirmed, :unconfirmed].include?(state)
-          if !result[state.to_s.capitalize]
+          unless result[state.to_s.capitalize]
             result[state.to_s.capitalize] = {}
           end
           result[state.to_s.capitalize][week.strftime('%W').to_i] = value
@@ -768,7 +768,7 @@ class Conference < ActiveRecord::Base
   def assert_keys_are_continuously(hash)
     keys = hash.keys
     (keys.min..keys.max).each do |key|
-      if !hash[key]
+      unless hash[key]
         hash[key] = 0
       end
     end
@@ -1004,7 +1004,7 @@ class Conference < ActiveRecord::Base
   # Adds a random color to the conference
   #
   def add_color
-    if !color
+    unless color
       self.color = get_color
     end
   end

app/models/contact.rb

@@ -7,7 +7,7 @@ class Contact < ActiveRecord::Base
             format: URI::regexp(%w(http https)), allow_blank: true
 
   def has_social_media?
-    return true if !facebook.blank? || !twitter.blank? || !googleplus.blank? || !instagram.blank? || !email.blank?
+    return true if facebook.present? || twitter.present? || googleplus.present? || instagram.present? || email.present?
     false
   end
 end

app/models/event.rb

@@ -115,9 +115,7 @@ class Event < ActiveRecord::Base
 
   def submitter
     result = event_users.where(event_role: 'submitter').first
-    if !result.nil?
-      result.user
-    else
+    if result.nil?
       user = nil
       # Perhaps the event_users haven't been saved, if this is a new proposal
       event_users.each do |u|
@@ -126,6 +124,8 @@ class Event < ActiveRecord::Base
         end
       end
       user
+    else
+      result.user
     end
   end
 
@@ -281,7 +281,7 @@ class Event < ActiveRecord::Base
   def generate_guid
     loop do
       @guid = SecureRandom.urlsafe_base64
-      break if !self.class.where(guid: guid).any?
+      break unless self.class.where(guid: guid).any?
     end
     self.guid = @guid
   end

app/models/venue.rb

@@ -44,7 +44,7 @@ class Venue < ActiveRecord::Base
   def generate_guid
     loop do
       @guid = SecureRandom.urlsafe_base64
-      break if !Venue.where(guid: guid).any?
+      break unless Venue.where(guid: guid).any?
     end
     self.guid = @guid
   end