Change DESCRIPTION to more modern look (dmlc#3179)

So other things can be added in comment field, such as ORCID.

R-package/DESCRIPTION

@@ -3,10 +3,19 @@ Type: Package
 Title: Extreme Gradient Boosting
 Version: 0.7.0.1
 Date: 2018-02-25
-Author: Tianqi Chen <[email protected]>, Tong He <[email protected]>,
-    Michael Benesty <[email protected]>, Vadim Khotilovich <[email protected]>,
-    Yuan Tang <[email protected]>
-Maintainer: Tong He <[email protected]>
+Authors@R: c(
+  person("Tianqi", "Chen", role = c("aut"),
+         email = "[email protected]"),
+  person("Tong", "He", role = c("aut", "cre"),
+         email = "[email protected]"),
+  person("Michael", "Benesty", role = c("aut"),
+         email = "[email protected]"),
+  person("Vadim", "Khotilovich", role = c("aut"),
+         email = "[email protected]"),
+  person("Yuan", "Tang", role = c("aut"),
+         email = "[email protected]",
+         comment = c(ORCID = "0000-0001-5243-233X"))
+  )
 Description: Extreme Gradient Boosting, which is an efficient implementation
     of the gradient boosting framework from Chen & Guestrin (2016) <doi:10.1145/2939672.2939785>.
     This package is its R interface. The package includes efficient linear