Fix Observable.skipLast alphabetization;

tests/observable.lua

@@ -262,9 +262,9 @@ describe('Observable', function()
   dofile('tests/retry.lua')
   dofile('tests/scan.lua')
   dofile('tests/skip.lua')
+  dofile('tests/skipLast.lua')
   dofile('tests/skipUntil.lua')
   dofile('tests/skipWhile.lua')
-  dofile('tests/skipLast.lua')
   dofile('tests/startWith.lua')
   dofile('tests/sum.lua')
   dofile('tests/switch.lua')

tools/concat.lua

@@ -40,9 +40,9 @@ local files = {
   'src/operators/retry.lua',
   'src/operators/scan.lua',
   'src/operators/skip.lua',
+  'src/operators/skipLast.lua',
   'src/operators/skipUntil.lua',
   'src/operators/skipWhile.lua',
-  'src/operators/skipLast.lua',
   'src/operators/startWith.lua',
   'src/operators/sum.lua',
   'src/operators/switch.lua',