Ubuntu: Add `gtkspell` for spellchecking

Adds spell checking support for zim using gtkspell.
zim: Use dedicated task file for installation

We also introduce configuration files.

This allows us to track the changes more easily.

The GOD list of pakages get's quite overwhelming.
git: Add todo for git config
zim: Add todo to install from deb package

The provided deb package in Ubuntu is too old
pidgin: Add task file

Just to remind me to document the setup.
Ubuntu: Add `freemind` package

See http://freemind.sourceforge.net/wiki/index.php/Main_Page