fix some file extensions

Task/Inverted-syntax/CoffeeScript/inverted-syntax.coffee

@@ -0,0 +1,8 @@
+alert "hello" if true
+alert "hello again" unless false # the same as the above; unless is a negated if.
+
+idx = 0
+arr = (++idx while idx < 10) # arr is [1,2,3,4,5,6,7,8,9,10]
+
+idx = 0
+arr = (++idx until idx is 10) # same as above; until is an inverted while.