Add a CITATION file containing paper information

inst/CITATION

@@ -0,0 +1,16 @@
+citHeader("To cite package dina in publications use:")
+
+citEntry(entry="Article",
+      title = "Bayesian estimation of the DINA model with Gibbs sampling",
+      author = personList(as.person("Steven Andrew Culpepper")),
+	  journal = "Journal of Educational and Behavioral Statistics",
+      year = "2015",
+      url = "http://www.hermanaguinis.com/pubs.html",
+      pdf = "http://www.hermanaguinis.com/ORM2015.pdf",
+      volume = "40",
+      number = "5",
+      pages = "454-476",
+      year = "2015",
+      doi = "10.3102/1076998615595403", 
+      textVersion = "Culpepper, S. A. (2015). Bayesian estimation of the DINA model with Gibbs sampling. Journal of Educational and Behavioral Statistics, 40, 454-476. DOI: 10.3102/1076998615595403.")
+