Switch to more standard config file location

[jmetz]

Instead of home directory dot file for the rc file, would suggest conforming to XDG standard, ie using $XDG_CONFIG_HOME (~/.config) and a folder within that, ie:

$XDG_CONFIG_HOME/gcalcli/config

which will usually resolve to $HOME/.config/gcalcli/config

[joshbode]

The .gcalcli_cache and .gcalcli_oauth could probably go to ${XDG_CACHE_HOME}/gcalcli/{cache,oauth}, also.

Note: ${XDG_CACHE_HOME} usually defaults to ${HOME}/.cache

[michaelmhoffman]

Looks like a good idea. The xdg-base-dirs package supplies these paths in a way that meets the standard.