deleting an app may not clean up all of DB

[dickhardt]

[nodejs.0] we received error:
[nodejs.0] TypeError: Cannot read property 'lawsample-dickhardt.dotcloud.com' of null
[nodejs.0] at exports.getAppKey (/home/dotcloud/app/lib/db_redis.js:469:30)
[nodejs.0] at /home/dotcloud/app/lib/db_redis.js:156:5
[nodejs.0] at try_callback (/home/dotcloud/node_modules/redis/index.js:520:9)
[nodejs.0] at RedisClient.return_reply (/home/dotcloud/node_modules/redis/index.js:590:13)
[nodejs.0] at ReplyParser.RedisClient.init_parser (/home/dotcloud/node_modules/redis/index.js:263:14)
[nodejs.0] at ReplyParser.EventEmitter.emit (events.js:96:17)
[nodejs.0] at ReplyParser.send_reply (/home/dotcloud/node_modules/redis/lib/parser/javascript.js:297:10)
[nodejs.0] at ReplyParser.execute (/home/dotcloud/node_modules/redis/lib/parser/javascript.js:198:22)
[nodejs.0] at RedisClient.on_data (/home/dotcloud/node_modules/redis/index.js:476:27)
[nodejs.0] at Socket. (/home/dotcloud/node_modules/redis/index.js:79:14)