Restore yaml metadata necessary for travis

_plugins/knit.r

@@ -4,7 +4,7 @@ library(bookdown)
 library(methods)
 
 args <- commandArgs(trailingOnly = TRUE)
-path <- args[1]
+path <- temp.Rmd
 
 if (!file.exists(path)) {
   stop("Can't find path ", path, call. = FALSE)

_plugins/rmarkdown.rb

@@ -21,13 +21,13 @@ module Jekyll
 
       # http://rubyquicktips.com/post/5862861056/execute-shell-commands
       content = `_plugins/knit.r temp.Rmd`
-      
+
       if $?.exitstatus != 0
-        raise "Knitting failed" 
+        raise "Knitting failed"
       end
-      
+
       content
       # File.unlink f.path
     end
   end
-end
+end