Merge pull request #66 from yupe/master

UPD: merge with yupe/master
UPD: откоментировал код в YDbMigration
UPD: dropColumn доработан для SQLite
UPD: добавил в YDbMigration expression, обёртка для SQLite CDbExpression
Merge pull request #843 from angel-kulikov/master

UPD: доработки по YDbMigration
UPD: protected/modules/comment/models/Comment.php меняем CDbExpression на YDbMigration::expression
UPD: protected/modules/news/models/News.php меняем CDbExpression на YDbMigration::expression
UPD: protected/commands/YQueueMailSenderCommand.php меняем CDbExpression на YDbMigration::expression
UPD: protected/modules/image/models/Image.php меняем CDbExpression на YDbMigration::expression
UPD: protected/modules/queue/models/Queue.php меняем CDbExpression на YDbMigration::expression
UPD: protected/modules/install/controllers/DefaultController.php меняем CDbExpression на YDbMigration::expression
UPD: protected/modules/user/components/UserIdentity.php меняем CDbExpression на YDbMigration::expression
UPD: protected/modules/user/models/User.php меняем CDbExpression на YDbMigration::expression
UPD: protected/modules/user/models/RecoveryPassword.php меняем CDbExpression на YDbMigration::expression
UPD: protected/modules/gallery/models/ImageToGallery.php меняем CDbExpression на YDbMigration::expression
UPD: protected/modules/dictionary/models/DictionaryGroup.php меняем CDbExpression на YDbMigration::expression
UPD: protected/modules/dictionary/models/DictionaryData.php меняем CDbExpression на YDbMigration::expression
UPD: protected/modules/feedback/controllers/DefaultController.php меняем CDbExpression на YDbMigration::expression
UPD: protected/modules/feedback/models/FeedBack.php меняем CDbExpression на YDbMigration::expression
UPD: protected/modules/yupe/models/Settings.php меняем CDbExpression на YDbMigration::expression