We saw a huge boost in number of reviews, overall rating, and sales when we started to solicit users in TapTyping (went from 3.5 to 4.5 stars). We made sure to only ask people once they had typed 2300 characters which equates to 3-4 speed tests or 1.5 typing lessons. Obviously the solicitation critera will be different for every app.

Not sure why you need a 3rd party library to do this though, it's pretty straight forward.