title: Shiny app turns grey (Disconnected from the server) when deployed, works fine locally
body: <p>I deployed an application
  This is my application: <a href="https://jleandroj.shinyapps.io/indicators/" rel="nofollow">https://jleandroj.shinyapps.io/indicators/</a>
  this is the repository: <a href="https://github.com/jleandroj/indicators" rel="nofollow">https://github.com/jleandroj/indicators</a></p>
  
  <p>ui.R</p>
  
  <pre><code>library(shiny)
  library(raster)
  library(sp)
  shinyUI(navbarPage("Global indicators",
  tabPanel("Main indicators",
  fluidPage(  
    imageOutput("distPlot",width = "100%",height = "400px"),
      hr(),
      fluidRow(
      column(9,
        h4("Ranking"),     
        dataTableOutput('table')
      ),  
      column(3,
      br(),
      checkboxGroupInput("checkGroup", label = h3("Social and economic   indicators"), 
                  choices = list('Breast cancer per 100th' = 'breastcancerper100th', 'HIV rate' = 'hivrate',
                                                                     'Suicide per 100th' = 'suicideper100th',
                                                                     'Oil per person' = 'oilperperson',
                                                                     'Alc consumption' = 'alcconsumption',
                                                                     'Polity score' = 'polityscore',
                                                                     'Armed forces rate' = 'armedforcesrate',
                                                                     'CO2 emissions' = 'co2emissions',
                                                                     'Income per person' = 'incomeperperson',
                                                                     'Female employ rate' = 'femaleemployrate',
                                                                     'Employ rate' = 'employrate',
                                                                     'Internet use rate' = 'internetuserate',
                                                                     'Electric per person' = 'relectricperperson'),selected = 'breastcancerper100th')
                )))
      ),
      tabPanel("About indicators",
               includeMarkdown("read.Rmd")
               )
  ))
  </code></pre>
  
  <p>server.R</p>
  
  <pre><code>library(shiny)
  library(raster)
  polygons &lt;- shapefile("data/TM_WORLD_BORDERS_SIMPL-0.3.shp")
  gap&lt;-read.csv("data/gapminder.csv",header = TRUE)
  names(gap)[1]&lt;-paste("NAME")
  
  shinyServer(function(input, output) {
  
  output$distPlot &lt;- renderPlot({
  
  polygons1 &lt;- merge(polygons,gap, by="NAME")
  
  spplot(polygons1,input$checkGroup, main=paste(input$checkGroup), lwd=.8, col="black")
  
  })
  
  output$table &lt;-  renderDataTable({ 
  
    gap2&lt;-subset(gap, select = c("NAME",input$checkGroup));
  
    gap2&lt;-gap2[with(gap2, order(-gap2[,2])),];
  
    gap2
  })
  })
  </code></pre>
  
  <p>When I deployed I get a gray screen with a message "Disconnected from the server"</p>
  
  <p>I have modified many options in settings and I added many libraries, I tried all But I got the same message.</p>
  
  <p>Thanks for helping me.</p>