Squashed commit of the following:

Closes #2

commit c925a4d4a49798f6a03c13deca3cd10626619ec8
Author: Lee Byron <lee@leebyron.com>
Date:   Sun Nov 20 15:04:24 2016 -0600

    update tests

commit 6b45037a1088cb55a7be11dcf2b25a443cc0ef37
Merge: daf7811 afe66ec
Author: Lee Byron <lee@leebyron.com>
Date:   Sun Nov 20 15:03:57 2016 -0600

    Merge branch 'master' of https://github.com/NicolasParada/rollup-plugin-async into NicolasParada-master

commit afe66ecc7ea5704cd64b7c805d5d8858f53a52f9
Author: Lee Byron <lee@leebyron.com>
Date:   Sun Nov 20 15:02:43 2016 -0600

    Add comments

commit b2f775f32eaf0562be693ef82c73652b46da7fe5
Author: Lee Byron <lee@leebyron.com>
Date:   Sun Nov 20 14:58:14 2016 -0600

    nl

commit c07cbe790cbcf2ab35a6e4565d3bc8153123cf8c
Author: Lee Byron <lee@leebyron.com>
Date:   Sun Nov 20 14:57:47 2016 -0600

    merge

commit 39143c17b4a177e7e04be4806a9df1718c389c54
Author: Lee Byron <lee@leebyron.com>
Date:   Sun Nov 20 14:56:48 2016 -0600

    unrelated

commit c1adab7cbd05e4b1af44413e4ce13cd01d0b5695
Author: Lee Byron <lee@leebyron.com>
Date:   Sun Nov 20 14:55:59 2016 -0600

    sp

commit 37d3a528818b7859192b476102b926f82363cb18
Author: NicolasParada <parada.nicolas@outlook.com>
Date:   Sat Nov 5 07:46:47 2016 -0300

    semicolon

commit 8e6797cce34c0e731dac4b2166ae796d079fe760
Author: NicolasParada <parada.nicolas@outlook.com>
Date:   Sat Nov 5 07:40:09 2016 -0300

    apply backslash replace only on win32

commit ac5094023385bc9bed6c90cca894664e91851616
Author: NicolasParada <parada.nicolas@outlook.com>
Date:   Tue Oct 18 16:32:36 2016 -0300

    update test

commit 250cf9fe1d5b8a5423eabcf7c9d5c43371fdd973
Author: NicolasParada <parada.nicolas@outlook.com>
Date:   Tue Oct 18 16:17:36 2016 -0300

    replaced const by var and added semicolons

commit 52feb9fa04f43f1690cf3463268fee1f60139054
Author: NicolasParada <parada.nicolas@outlook.com>
Date:   Tue Oct 18 16:12:42 2016 -0300

    path: replace backslashes by forward slashes

index.js

@@ -7,7 +7,7 @@ var createFilter = require('rollup-pluginutils').createFilter;
 module.exports = function(options) {
   options = options || {};
   var filter = createFilter(options.include, options.exclude);
-  const sourceMap = options.sourceMap !== false;
+  var sourceMap = options.sourceMap !== false;
 
   return {
     name: 'async-to-gen',
@@ -44,5 +44,9 @@ function getAsyncHelperFile() {
       fs.unlinkSync(_asyncHelperFile)
     })
   }
-  return _asyncHelperFile;
+  
+  // Note that while win32 uses \ as path separator, Node require() may rely on /.
+  return os.platform() === 'win32' ?
+    _asyncHelperFile.replace(/\\/g, '/') :
+    _asyncHelperFile;
 }