exclude repository-settings from source-package generated via 'git archive'

.gitattributes

@@ -13,3 +13,10 @@ CHANGES text eol=lf
 CREDITS text eol=lf
 LICENSE text eol=lf
 Readme.md text eol=lf
+# make sure that repo-specific settings (.gitignore, CI-setup,...)
+# are excluded from the source-package generated via 'git archive'
+.git*      	export-ignore
+/.travis*	export-ignore
+/.coveralls*	export-ignore
+appveyor.yml	export-ignore
+