Returned some formatting to the output of the "cta archivefile ls" command

Changed the type of the ListArchiveFilesCmd::m_readBuffer
member-variable from std::string to std::ostringstream. This
modification will make it much easier to add output
formatting for the "cta archivefile ls" command in the
future.

Moved the path column of the output of the "cta archivefile ls"
command to the very end of the line.  This was done because the
path column is the only real random width column.

The "cta af ls" command now sends several rows back to the client
in a single reply.

Set the header colour of the "cta af ls -h" command back to red

First version of a streaming "cta archivefile ls" command.