testing: Limit the backends we use for SLF4J
testing: Limit the backends we use for SLF4J

Using KazooTestCase becomes really chatty if you happen to have other
backends than just log4j installed for slf4j. Limiting only to
slf4j-log4j-* ensures that the properties file we provide when
starting zookeeper is enough to turn off the chatter.

kormat/kazoo,jacksontj/kazoo,jacksontj/kazoo,python-zk/kazoo,harlowja/kazoo,python-zk/kazoo,AlexanderplUs/kazoo,max0d41/kazoo,bsanders/kazoo,tempbottle/kazoo,max0d41/kazoo,rockerbox/kazoo,rackerlabs/kazoo,rackerlabs/kazoo,harlowja/kazoo,tempbottle/kazoo,rgs1/kazoo,pombredanne/kazoo,pombredanne/kazoo,AlexanderplUs/kazoo,Asana/kazoo,bsanders/kazoo,rgs1/kazoo,rockerbox/kazoo,kormat/kazoo