title: Problems locale language with converting string to dates
body: <p>I have problems with converting strings into dates. First I encountered the problem and figured out that as.chron is using the Dutch abbrevations. Therefore I thought that changing the locale would solve this problem. However after doing this I still have the same problem and I can not figure out where to adjust the language as.chron uses.</p>
  
  <p>Input</p>
  
  <pre><code>require("chron")
  Sys.setlocale(category = "LC_ALL", locale = "English")
  as.chron("Mrt 12, 2015", format = "%b %e, %Y") #The dutch abbrevation
  as.chron("Mar 12, 2015", format = "%b %e, %Y")
  </code></pre>
  
  <p>Output</p>
  
  <pre><code>Sys.setlocale("LC_ALL","English")
  [1] "LC_COLLATE=English_United States.1252;LC_CTYPE=English_United         States.1252;LC_MONETARY=English_United States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252"
  &gt; as.chron("Mrt 12, 2015", format = "%b %e, %Y")
  [1] (03/12/15 00:00:00)
  &gt; as.chron("Mar 12, 2015", format = "%b %e, %Y") 
  [1] (NA NA)
  </code></pre>