Update readable-stream dependency to 3.x

[pravi]

Currently this module uses readable-stream 2.x and it'd be good to update the dependency to readable-stream 3.x

[pravi]

When trying to use readable-stream 3.x it gives this error,

Error: Cannot find module 'readable-stream/transform'
Require stack:
- /usr/share/nodejs/replacestream/index.js
- /usr/share/nodejs/gulp-replace/index.js

[pravi]

Changing 'readable-stream/transform' to "readable-stream").Transform should fix this.