Work around yum's line breaks

yum uses urllib's(!) idea of the terminal width to make its output
fit into the terminal. Sadly, when no terminal at all is used,
yum assumes 20 characters and breaks the lines after the package
name or the version string which causes apt-dater-host fail to
parse the line

Implement a wrapper around open(FOO, "yum bar |") that replaces
/\n+(\s+)/ by $1 so the caller will get the line joined back
together.