Add ggplot2 support und bump to v0.2.0

Change-Id: Iee69051bc64fb9fbde55bbea61c7e892ff95229d
diff --git a/.Rbuildignore b/.Rbuildignore
index 0c1c641..21ae968 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -2,3 +2,4 @@
 ^\.Rproj\.user$
 LICENSE.md
 Readme.md
+Changelog.md