Update version launch date.

R/DESCRIPTION

@@ -1,7 +1,7 @@
 Package: prophet
 Title: Automatic Forecasting Procedure
 Version: 0.1.1
-Date: 2017-01-26
+Date: 2017-04-17
 Authors@R: c(
   person("Sean", "Taylor", email = "sjt@fb.com", role = c("cre", "aut")),
   person("Ben", "Letham", email = "bletham@fb.com", role = "aut")