zsh: make color_map and attr_map more robust

zsh allows to defile "global aliases" which may appear anywhere on the
command line. The most prominent example is:

  alias -g 'L'=" | less "

This allows command lines such as "bzr log L".

In order to avoid such global aliases to be expanded in this
user-sourced utility file, the key need to be quoted.
byobu-reconnect-sockets: quote shell expansions

this avoids error messages in zsh
* usr/bin/byobu: LP: #1176956
  - handle unlimted ulimits
* usr/bin/byobu-reconnect-sockets, usr/lib/byobu/include/shutil: LP: #1162432
  - fix reconnect on zsh
* usr/share/man/man1/byobu.1: LP: #1121414
  - document PuTTY UTF-8 configuration
    + thanks to Chris Holmes
* usr/bin/byobu-keybindings, usr/bin/Makefile.am,
  usr/share/man/man1/byobu-keybindings.1,
  usr/share/man/man1/Makefile.am: LP: #1118755
  - added a new executable and manpage: byobu-keybindings
  - this is a command line utility for toggling Byobu's keybindings
    on an off
  - useful when Shift-F12 is not usable (Linux console tty), and
    when ctrl-a-! is not usable (tmux)