Add native to-/fromJSArray
Make error message a bit better

When elm_dependencies.json is not found, give a bit more guidance.
resolve #538, correct error for appendable
point to elm-lang git repo
Merge pull request #602 from juhp/patch-1

point to elm-lang git repo
Add Array.to/fromJSArray tests
Array.to/fromJSArray to Native.Array
Fix parantheses
Move to [1..] instead of initialize
Merge branch 'pr/603'

Conflicts:
	tests/elm/Test/Array.elm
Fix silly type error with Array tests
Clean up tests for String library
Rename String.sub to String.slice and add tests

Name change to get it to match Array library. May be good to bring
left, right, dropLeft, and dropRight function to the Array library.
Adjust tests to get better expected/actual errors
Make meaning of Array.slice match String.slice

This is the meaning used by JS, Python, Clojure, and Scala at least. I
hope Dijkstra would be pleased.
Get zero-indexing right in get examples