title: fun.y not recognized in ggplot
body: <p>I am trying to plot a mean line and a quintile line using <code>ggplot2</code>. </p>
  
  <pre><code>DF&lt;-data.frame(DOB = c(1965, 1949, 1964, 1979, 1960, 1992, 1991, 1963, 1964, 1992, 1971, 1965),
                 trip.duration.hr =c(3.36, 2.25, 5.31, 10.7, 1.96, 4.33, 23.55, 3.92, 5.46, 3.45, 13.72, 7.33))
  </code></pre>
  
  <p>I have inserted my code below. When I try to run it, it gives me the following error message:</p>
  
  <blockquote>
    <p>No summary function supplied, defaulting to <code>mean_se()</code></p>
    
    <p>No summary function supplied, defaulting to <code>mean_se()</code></p>
    
    <p>Warning messages:</p>
    
    <p>1: Ignoring unknown parameters: fun.y 
    2: Ignoring unknown parameters: fun.y 
    3: Removed 40135 rows containing non-finite values (stat_summary). 
    4: Removed 40135 rows containing non-finite values (stat_summary). 
    5: Removed 40216 rows containing missing values (geom_point). </p>
  </blockquote>
  
  <p>My code below: </p>
  
  <pre><code>ggplot(DF, aes(x=DOB, y=trip.duration.hr)) +
    geom_jitter(alpha=1/10) +
    geom_line(stat = 'summary', fun.y = "mean", color="orange", size=1) +
    geom_line(stat = 'summary', fun.y = "quantile", fun.args = list(probs = .9), linetype=2, color="red")
  </code></pre>