title: Error in calling Stanford sentiment parser in Syuzhet R package
body: <p>I tried to call the Stanford sentiment analyzer from Syuzhet R package.  I followed the instructions in the reference manual and vignettes from the Cran site. I installed the Stanford CoreNLP package on my machine and it works fine standalone. However, when I called the Stanford sentiment analyzer from R, I got the following error:<br>
  <strong><em>Error in system(cmd, input = text_vector, intern = TRUE, ignore.stderr = TRUE) : 'cd' not found</em>.</strong><br>
   I searched the web, but couldn't find a solution. Here is my code:</p>
  
  <pre><code>library(syuzhet)
  test &lt;- c("I am a very happy person.", "I am a very sad person.")
  tagger_path &lt;-  "C:/Users/sqchen/Documents/R/stanford-corenlp-full-2015-12-09"
  stanford_vector &lt;- get_sentiment(test, method="stanford", tagger_path)
  </code></pre>
  
  <p>Calling an alternative method <em>get_stanford_sentiment</em> gave the some error. Your help is appreciated.</p>