title: Adjust title vertically to inside the plot - vjust not working
body: <p>I want to place the title inside the plot instead at the default top position.
  Here is a simple code snippet</p>
  
  <pre><code>library(ggplot2)
  df &lt;- data.frame(x = c(1:10), y = rnorm(10, 1, 2))
  ggplot(df, aes(x, y))+
     geom_line() +
     ggtitle("Demo") + 
     theme(plot.title = element_text(vjust = -3)) 
  </code></pre>
  
  <p>In the past I was able to do this by varying <code>vjust</code> value, but now it is not working. Any idea how to do this?</p>