Indexes Using columns not quoted

[toddpi314]

If you have a case-sensitive model attribute and create a mutli-column index like this:

var User = schema.define('User', {
    userId: {
        type: Number
    },
    messageId: {
        type: Number
    }
}, {
    indexes: {
        indexPrimary: {
            columns: 'userId,messageId',
            type: 'btree'
        }
    }
});

The constructed sql doesn't wrap the column names for the btree's Using context:

CREATE  INDEX "indexPrimary" ON "User" USING btree (userId,messageId)

This will result in something like "Cannot find column 'userid'" failure.

Workaround (manually adding the quotes inline):

        indexPrimary: {
            columns: '"userId","messageId"',
            type: 'btree'
        }

I am guessing that this should be handled in the library itself, as it does this for single columns perfectly.

Thanks for the hard work!