title: savewidget from htmlwidget in R , cannot save html file in another folder
body: <p>I have a map leaflet that I want to save in an html file in a specific folder.
  I am using Windows 7.</p>
  
  <p>I tried the following :</p>
  
  <pre><code>library(htmlwidgets)
  saveWidget(map_leaflet, file="ressources/test.html")
  
  library(htmlwidgets)
  saveWidget(map_leaflet, file="ressources\\test.html")
  
  library(htmlwidgets)
  path_name &lt;- file.path("ressources", "test.html", fsep="\\")
  saveWidget(map_leaflet, file=path_name)
  
  library(htmlwidgets)
  path_name &lt;- paste("ressources", "test.html", sep="/")
  saveWidget(map_leaflet, file=path_name)
  </code></pre>
  
  <p>As an error message, depending on the Rstudio session, I either have</p>
  
  <p>1) Error in setwd(dir) : cannot change working directory</p>
  
  <p>2) Cannot find path</p>
  
  <p>When I only save like this :</p>
  
  <pre><code>library(htmlwidgets)
  saveWidget(map_leaflet, file="test.html")
  </code></pre>
  
  <p>It works perfectly.</p>
  
  <p>Thank you in advance for your help.</p>