Fails for image file names containing spaces

[cristim]

Steps to reproduce

• Check out my project containing a gulpfile.js using this library: git clone https://github.com/cristim/img-to-base64-html-converter.git
• cd img-to-base64-html-converter && npm install
• Save a website which contains spaces in the file name, the easiest is to use the above URL, and save the page to the same directory, using the "Save as" context menu(I did it in Chrome).
• running gulp in the same directory would return this error

[23:25:18] Using gulpfile /tmp/test/img-to-base64-html-converter/gulpfile.js
[23:25:18] Starting 'default'...
[23:25:18] Finished 'default' after 12 ms
mtype:  application/octet-stream
mtype:  application/octet-stream
mtype:  image/gif
/tmp/test/img-to-base64-html-converter/cristim_img-to-base64-html-converter_%20Converts%20external%20images%20referenced%20from%20an%20HTML%20file%20into%20inlined%20base64%20img%20tags_files/octocat-spinner-32.gif image/gif
fs.js:640
  return binding.open(pathModule._makeLong(path), stringToFlags(flags), mode);
                 ^

Error: ENOENT: no such file or directory, open '/tmp/test/img-to-base64-html-converter/cristim_img-to-base64-html-converter_%20Converts%20external%20images%20referenced%20from%20an%20HTML%20file%20into%20inlined%20base64%20img%20tags_files/octocat-spinner-32.gif'
    at Error (native)
    at Object.fs.openSync (fs.js:640:18)
    at Object.fs.readFileSync (fs.js:508:33)
    at .<anonymous> (/tmp/test/img-to-base64-html-converter/node_modules/gulp-img64/index.js:37:23)
    at exports.each (/tmp/test/img-to-base64-html-converter/node_modules/cheerio/lib/api/traversing.js:226:24)
    at Transform._transform (/tmp/test/img-to-base64-html-converter/node_modules/gulp-img64/index.js:27:13)
    at Transform._read (/tmp/test/img-to-base64-html-converter/node_modules/gulp-img64/node_modules/readable-stream/lib/_stream_transform.js:184:10)
    at Transform._write (/tmp/test/img-to-base64-html-converter/node_modules/gulp-img64/node_modules/readable-stream/lib/_stream_transform.js:172:12)
    at doWrite (/tmp/test/img-to-base64-html-converter/node_modules/gulp-img64/node_modules/readable-stream/lib/_stream_writable.js:237:10)
    at writeOrBuffer (/tmp/test/img-to-base64-html-converter/node_modules/gulp-img64/node_modules/readable-stream/lib/_stream_writable.js:227:5)

Apparently the spaces in the file name get escaped, which causes the failure.

Prepending file:// to the same string may fix it.