Fix minor mistake in README
Fix typo in getopt specification

The --verbose long option was not properly recognized.
Break common shift statements out of case block
Capitalize 'program' variable
Allow config files to override settings
Capitalize variables
Order variables alphabetically
Add -c,--config option

Takes a file and adds it to the list of config files. Can be specified
multiple times, later files override earlier ones.
Let options override config settings
Exit if no pass-name is given
Greatly improve usage message
Add -h,--help option
Add defaults to usage message
Print encoded image to stdout if VIEWER_EXEC is '-'
Add -w, --viewer option
Remove extra '-' parameter to viewer
Attempt to find image viewer automatically if unset
Add --version option
Rename source files

- Rename passqr to passqr.sh and unset executable flag
- Rename password-store-qr to passqr.bash-completion

The make script will still install them to the same respective locations.
Remove unnecessary PKGNAME from makefile