title: readr : Turn off scientific notation in write_csv
body: <p>I am using R to process Census data which uses really long numeric GEOIDs to identify the geographies. The issue I am facing is when writing out the processed data using <code>write_csv</code> (from the <code>readr</code> package) it is writing these GEOIDs in scientific notation. Is there a way to get around this?</p>
  
  <p>Note: I am able to toggle scientific notation display on R console using by setting the <code>scipen</code> option to a sufficiently large value. But this setting does not seem to extend into the <code>readr</code> library.</p>
  
  <p>Here is a toy dataset:</p>
  
  <pre><code>library(dplyr)
  library(readr) # which is the package with write_csv
  (tbl_df(data.frame(GEOID = seq(from=60150001022000, to=60150001022005, 1))))
  Source: local data frame [6 x 1]
  
             GEOID
  1 60150001022000
  2 60150001022001
  3 60150001022002
  4 60150001022003
  5 60150001022004
  6 60150001022005
  
  write_csv((tbl_df(data.frame(GEOID = seq(from=60150001022000, to=60150001022005, 1)))), "test.csv")
  </code></pre>
  
  <p>This is what I am getting currently. I am looking for a way to get the same numbers as above:</p>
  
  <pre><code>GEOID
  6.02E+13
  6.02E+13
  6.02E+13
  6.02E+13
  6.02E+13
  6.02E+13
  </code></pre>