title: Sys.Date() shows wrong date in shiny apps
body: <p>This code should show me yesterday as date for start and end with today as the last option.
  It worked for several month, I did not change anything, but since some weeks I get the wrong date.</p>
  
  <p>It shows me the day before yesterday if I run this code locally, rstudio on my ubuntu server or connect to shiny server running this code.</p>
  
  <pre><code>Sys.setenv(TZ='GMT')
  
  shinyApp(
    ui &lt;- basicPage(
      dateRangeInput("daterange", "Daterange",start = Sys.Date()-1
                     ,end = Sys.Date()-1,max=Sys.Date())
    ),
    server &lt;- function(input,output){}
  )
  </code></pre>
  
  <p>I found this question, <a href="https://stackoverflow.com/questions/30254875/in-shiny-for-r-why-does-sys-date-return-yesterdays-date-inside-a-dateinput">In Shiny for R, why does Sys.Date() return yesterday&#39;s date inside a dateInput?</a>, and 
  with start=NULL,end=NULL I get correctly today, but as I need yesterday this is no solution for me.</p>
  
  <p>If I run Sys.Date() in the console it gives me the right date, locally and on my server. The problem only occurs if I run this as a shiny app.</p>
  
  <hr>
  
  <h2>Update 21.10.2015</h2>
  
  <p>I tried a bit around thanks to Oskar Forsmo's suggestion to get system("date") inside the app, which gives me the correct date and time.</p>
  
  <p>And it gets even more strange: </p>
  
  <pre><code>library(shiny)
  
  values &lt;- reactiveValues()
  
  shinyApp(
    ui &lt;- basicPage(
      uiOutput("timerange"),
      textOutput( "today" )
  
    ),
    server &lt;- function(input,output){
  
      isolate(values$day &lt;- Sys.Date())
  
      output$today &lt;- renderText({
        as.character(values$day-1)
      })
  
     output$timerange &lt;- renderUI({ dateRangeInput("daterange", "Daterange",start = values$day-1
                     ,end = values$day-1,max=values$day) })
  
    })
  </code></pre>
  
  <p>In the output object "today" I have the correct date, in the uiOutput "timerange" I have the wrong day, it shows again the day before yesterday.</p>
  
  <p>I'm gonna provide a screenshot, because I would not believe myself.</p>
  
  <p><a href="https://i.stack.imgur.com/w6hwX.jpg" rel="nofollow noreferrer">wrong day in dateRangeInput, right in textOutput</a></p>
  
  <p>And on top of that, the app run on shiny server shows the correct time/date to some of my collegues and some get the same wrong date.</p>
  
  <p>To isolate the error, as I have the correct day in renderText there must be a problem somewhere with the dateRangeInput object which is triggered by my desktop?!</p>
  
  <hr>
  
  <h2>Update 29.10.2015</h2>
  
  <p>I did not change anything on the code/server but it shows now the correct date, have no idea why but it works as of today.. if anybody have an idea why this happens i would really appreciate to know.</p>