update travis script to build on julia nightlies
update travis script to build on julia nightlies

multidis/BlackBoxOptim.jl,JuliaPackageMirrors/BlackBoxOptim.jl,tkelman/BlackBoxOptim.jl,multidis/BlackBoxOptim.jl,JuliaPackageMirrors/BlackBoxOptim.jl,multidis/BlackBoxOptim.jl,tkelman/BlackBoxOptim.jl,JuliaPackageMirrors/BlackBoxOptim.jl,tkelman/BlackBoxOptim.jl