libaur: Make the downloading the same as cower
pywer: Error when run without a config file
pywer: Allow `pywer -h` without a config file
pywer: Allow you to override the config
pywer: Add --target option
Allow multiple args to certain operations

-i, -u and -d have the ability to take multiple arguments, so use the
nargs option to allow this.

-u can also be run without arguments, but can optionally take a single
package name just to check for that update alone.
todo: fix spelling mistake
libaur: Clean up UpdatedPkgs

Having the list be specified only for a certain command was silly. Just
default to an empty list, but do it in __init__.