This is achieved by storing the absolute path to the dotfile directory in the
variable $DOTFILES_LOCATION. And change every hardcoded location into the
dotfiles with this var.
The Variable $DOTFILES_LOCATION populated with the output of
get_dotfiles_location.sh at 3 places:   1) config.fish | zshrc
                                        2) xinitrc (should be allready exported)

get_dotfiles_location uses the assumption that it is symlinked into the dotfiles
directory.

offlineimap:    * include patch for offlineimap
                * change config to the small one
                * include environment file in systemd unit

setup.py:       * handle offlineimap situation
                    * print a warning and prompt for proceeding
                    * write the environment file for the systemd unit
                * add pseudo dependency (get_dotfiles_location)
                    to [fish-config, offlineimap, i3]
                * print errors on stderr
                * don't exit if a function fails

config.fish:    * export $DOTFILES_LOCATION
                * change hardcoded links
                * add perl tools to path
                * export some yaourt specific vars if yaourt is available

zshrc: export $DOTFILES_LOCATION

xinitrc: export $DOTFILES_LOCATION

i3/*: change hardcoded links

scripts/* change hardcoded links

README.md: mention $DOTFILES_LOCATION

README.md:              mention that some scripts uses hardcoded locations

scripts/media_is_spotify_playing.sh:    use dbus to get spotify PlaybackStatus

scripts/media_control:  1) introduce a new file: /tmp/media_control_last
                        2) use this file to store the last active player
                        3) send the command to the last active player if no
                            player is running