Updated bash-completion to 2.1

An extensive changelog is readable here:

http://bash-completion.alioth.debian.org/files/CHANGES-1.1
http://bash-completion.alioth.debian.org/files/CHANGES-1.2
http://bash-completion.alioth.debian.org/files/CHANGES-1.3
http://bash-completion.alioth.debian.org/files/CHANGES-2.0
http://bash-completion.alioth.debian.org/files/CHANGES-2.1
Removed unnecessary comments
Updated shells/bash-completion to 2.1