added explicit export list to Http.elm
added explicit export list to Http.elm

laszlopandy/core,Dandandan/core,alexiamcdonald/elm-core,krisajenkins/core,colinmccabe/core,bradurani/core,rick68/core,ThomasWeiser/core,manleyjster/core,Pisys/core,eeue56/core,alexiamcdonald/elm-core,rgrempel/core,martinos/core,simonh1000/core,isaacsanders/core,krisajenkins/core,vilterp/core,ThomasWeiser/core,rick68/core,suryagaddipati/core,laszlopandy/core,martinos/core,Dandandan/core,bradurani/core,isaacsanders/core,simonh1000/core,eeue56/core,colinmccabe/core,suryagaddipati/core,vilterp/core,Pisys/core,manleyjster/core,rgrempel/core