Support for moving the config directory on linux.
Current location of the configuration directory on linux is `$HOME/.gitkraken/`. The freedesktop XDG Base Directory Specification suggests putting it in `$XDG_CONFIG_HOME/gitkraken` (by default `XDG_CONFIG_HOME=$HOME/.config/`).
Permanently moving the directory would be a breaking change, but many applications are using an environment variable to change this location on a per user basis. (e.g. for gtk2 I can do `export GTK2_RC_FILES="$XDG_CONFIG_HOME"/gtk-2.0/gtkrc
This helps keeping users' directories clean, and allows for easier tracking of configuration files (for example for backup purposes).
If this is already an option, I was unable to find it in the documentation.