title: ggsave scale does not scale text size
body: <p>Whenever I save a plot using ggsave and scale, the size of the plot goes up, but not the size of the text.</p>
  
  <pre><code>ggplot(economics, aes(date, unemploy)) + 
    geom_line(color="#2fb2ab") +
    theme_ipsum() +
    theme(
      text = element_text(family="Georgia"),
      axis.title.x = element_text(hjust=0.5, size=13, family="Georgia"),
      axis.title.y = element_text(hjust=0.5, size=13, family="Georgia"),
      panel.border = element_rect(colour = "black", fill=NA))+
    ylab("Unemployment") +
    xlab("Date")
  
  ggsave("sample_graph.png", scale = 2)
  ggsave("sample_graph2.png", scale = 3)
  </code></pre>
  
  <p>Here is graph 1:</p>
  
  <p><a href="https://i.stack.imgur.com/UVfvX.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/UVfvX.png" alt="graph 1, scale = 2"></a></p>
  
  <p>Here is graph 2:</p>
  
  <p><a href="https://i.stack.imgur.com/UMFkW.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/UMFkW.png" alt="graph 2, scale = 3"></a></p>
  
  <p>How do I get it to scale both the graph size and the font? I don't want to manually set the height and width. </p>