OSX: avoid ._-files being created in tar archives

Well known

tar cfz file.tar.gz sources...

may create strange .-files, i.e. OSX resource files, inside the archive. To avoid this, set the following env in .bashprofile

export COPYFILE_DISABLE=1

If this doesn't work, try to find out the correct name, as it differs in some versions of osx tar

strings /usr/bin/tar|grep DISABLE