adding shell script for creating a new smb account

will be leveraged by a puppet class; only tested against Ubuntu 12.04
adding a shell script for checking whether a samba account exists for a given user

will be leveraged by a puppet class; only tested against Ubuntu 12.04
enabling installation of samba account checking/creation shell scripts
enabling configuration to enumerate users who can access a given share

adding support for "valid users" smbd.conf configuration option to samba::server::share
correcting read_only configuration application

"read only" option was not removable due to "read_only" misspelling
adding defined type for ensuring presence of a samba account for a given user

user is identified by name, and a password must be given
in its current state this can only create a user (with a given password), but will not update passwords (would need to figure out how to introspect on whether an in-place password differs from plaintext password input)
also, this currently assumes/requires that a Unix user account with a matching name exists
correcting variable tested for presence of valid_users input
correcting syntax used to apply "valid users" share configuration
clean up whitespace