Synced gitignores with github repo (#1245)

* Renamed scripts directory into contrib

* Added script to download gitignores from github

* Synced gitignores with github repo

options/gitignore/R

@@ -2,9 +2,18 @@
 .Rhistory
 .Rapp.history
 
+# Session Data files
+.RData
+
 # Example code in package build process
 *-Ex.R
 
+# Output files from R CMD build
+/*.tar.gz
+
+# Output files from R CMD check
+/*.Rcheck/
+
 # RStudio files
 .Rproj.user/
 
@@ -14,3 +23,11 @@ vignettes/*.pdf
 
 # OAuth2 token, see https://github.com/hadley/httr/releases/tag/v0.3
 .httr-oauth
+
+# knitr and R markdown default cache directories
+/*_cache/
+/cache/
+
+# Temporary files created by R markdown
+*.utf8.md
+*.knit.md