Add .gitattributes during repo initialization (#352)

Make `blackbox_initialize` include `.blackbox/.gitattributes` when
creating a new repository.

Closes #351

Signed-off-by: Joe Block <jpb@unixorn.net>

bin/blackbox_initialize

@@ -44,7 +44,7 @@ if [[ $VCS_TYPE = "git" ]]; then
   grep -qF "$LINE" "$FILE" || echo "$LINE" >> "$FILE"
   LINE='blackbox-files.txt text eol=lf'
   grep -qF "$LINE" "$FILE" || echo "$LINE" >> "$FILE"
-
+  vcs_add "$FILE"
 fi
 
 if [[ $VCS_TYPE = "svn" ]]; then