upgrade r-base to R 3.4.0 released last Friday

library/r-base

@@ -1,5 +1,5 @@
 # maintainer: "Carl Boettiger" <[email protected]> (@cboettig)
 # maintainer: "Dirk Eddelbuettel" <[email protected]> (@eddelbuettel)
 
-3.3.3: git://github.com/rocker-org/rocker@8620b7759022c7860ac54887066b79d224fe01dd r-base
-latest: git://github.com/rocker-org/rocker@8620b7759022c7860ac54887066b79d224fe01dd r-base
+3.4.0: git://github.com/rocker-org/rocker@e9758030e435915d5e6f21aaab0fc35a5a8efaae r-base
+latest: git://github.com/rocker-org/rocker@e9758030e435915d5e6f21aaab0fc35a5a8efaae r-base