Fix error in git info display

Fix the error displayed when no upstream.
[mutt] keybindings in pager mode
[mutt] layout is now link to environment variable
[mutt] signature for gmail
zsh config uses oh-my-zsh and is a whole direcory
[cmus] remove bindings before adding new ones
[zsh] remove deprecated .zshrc
[zsh] update dotsync
[bootstrap] update

Not fully tested yet.

the update is especially link to the new zsh config.
[msmtp] template
[offlineimap] template