fix sort_spec.rb

Since the original ascending? is split into two functions:  ascending?
and non_descending? which have different meanings.

```ruby
    sample = [31, 37, 26, 30, 2, 30, 1, 33, 5, 14, 11, 13, 17, 35, 4]
```

The sample in the spec is has duplicate elements, therefor it is not
ascending (monotonically increasing order) but non-descending
(monotonically non-decreasing order).  So I had to change
“Functional.ascending?(sorted)” to  “Functional.non_descending?(sorted)”
change and add spec for ascending? and friends
travis ci add ruby 2.1.1 and rbi 2.2.2