Weather segment - restore print existing on failure
Weather segment - restore print existing on failure

I took this out before and have now noticed that occasionally there is a
timing issue that causes the weather segment to flash and return. I know
that this could potentially annoy others, so I wanted to restore this
portion.

Also a few minor formatting changes.

tacahiroy/tmux-powerline,tacahiroy/tmux-powerline,tacahiroy/tmux-powerline