Check for 0.4, otherwise install SpecialFunctions

Author: ararslan

test/DualTest.jl

@@ -6,7 +6,11 @@ using ForwardDiff: Partials, Dual, value, partials
 
 import NaNMath
 import Calculus
-importall SpecialFunctions
+
+if VERSION >= v"0.6.0-dev.2767"
+    Pkg.installed("SpecialFunctions") === nothing && Pkg.add("SpecialFunctions")
+    importall SpecialFunctions
+end
 
 samerng() = MersenneTwister(1)