hello-world: Update to fit the new canonical data

Author: SaschaMann

config.json

@@ -8,8 +8,7 @@
       "slug": "hello-world",
       "difficulty": 1,
       "topics": [
-        "strings",
-        "string interpolation"
+        "strings"
       ]
     },
     {

exercises/hello-world/example.jl

@@ -1,3 +1,3 @@
-function hello(name::AbstractString="World")
-    return "Hello, $(name)!"
+function hello()
+    return "Hello, World!"
 end

exercises/hello-world/runtests.jl

@@ -2,11 +2,6 @@ using Base.Test
 
 include("hello-world.jl")
 
-@testset "no name" begin
+@testset "Say Hi!" begin
     @test hello() == "Hello, World!"
 end
-
-@testset "names" begin
-    @test hello("Alice") == "Hello, Alice!"
-    @test hello("Bob") == "Hello, Bob!"
-end