Make license handling cran and github compliant

Change-Id: I38e1800bd32f6bcad5b570570283583c9484e961
diff --git a/.Rbuildignore b/.Rbuildignore
index 6806493..8f7d35b 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -2,3 +2,4 @@
 ^\.Rproj\.user$
 ^Readme.md
 ^cran-comments.md
+^LICENSE\.md$