RPM Creation to simplify installation process

Hi Gina,

I've made some modifications on the code to create a RPM package that make install process easy.
- The software is installed in /opt/todo.txt
- A symbolic link is created in /usr/bin/todo pointing to /opt/todo.txt/todo.sh
- The autocompletion script is added in /etc/bash_completion.d/
- A script is added in /etc/profile.d/ to make autocompletion availabe (without it, it does not work)

The modification that I've made are explained in the commit that I've done. Take a little bit of time to look!

The package are built on opensuse build service here: https://build.opensuse.org/package/show?package=todo.txt&project=home%3Aimclem

The package repositories are available here:
http://download.opensuse.org/repositories/home:/imclem/

The installation is quite simple:
- Choose the repo corresponding to your distro (in the following instruction I choose centos 6)
- Then get the repo file, so as root
http://download.opensuse.org/repositories/home:/imclem/CentOS_CentOS-6/home:imclem.repo -O /etc/yum.repos.d/todo.txt.repo
- Then perform install 
sudo yum install todo.txt

Each user can youse "todo" command in a separated environment. At first use a todo directory is created in user home dir. User can override default config as usual.

I actually need some tester, I will be testing on Fedora 17.

Best Regards,

Clément