Add test for API.lookup_users.
Add test for API.lookup_users.

nickmalleson/tweepy,hackebrot/tweepy,abhishekgahlot/tweepy,bconnelly/tweepy,cinemapub/bright-response,cogniteev/tweepy,kskk02/tweepy,raymondethan/tweepy,conversocial/tweepy,yared-bezum/tweepy,LikeABird/tweepy,kcompher/tweepy,abhishekgahlot/tweepy,sidewire/tweepy,iamjakob/tweepy,nickmalleson/tweepy,cinemapub/bright-response,wjt/tweepy,tuxos/tweepy,sa8/tweepy,elijah513/tweepy,nickmalleson/tweepy,aleczadikian/tweepy,edsu/tweepy,IsaacHaze/tweepy,markunsworth/tweepy,atomicjets/tweepy,kylemanna/tweepy,rudraksh125/tweepy,arunxarun/tweepy,thelostscientist/tweepy,nickmalleson/tweepy,techieshark/tweepy,zhenv5/tweepy,robbiewoods05/tweepy,aganzha/tweepy,takeshineshiro/tweepy,markunsworth/tweepy,vivek8943/tweepy,Choko256/tweepy,awangga/tweepy,vikasgorur/tweepy,srimanthd/tweepy,tweepy/tweepy,obskyr/tweepy,damchilly/tweepy,tsablic/tweepy,svven/tweepy,vishnugonela/tweepy,truekonrads/tweepy