support 'old style' partition sizes (1M, 1G) and percentages (25%-50%)

Values like '1G' are supported now but using these 'units' provokes a
depreciation warning since these values could be interpreted as
base10 (Gigabyte / GB) or base2 (Gigibyte / GiB). The user should make
it clear which one is intendend by using the correct unit (GB or GiB).
update testconfig to use 'GiB' instead of 'G'

(This avoids a warning message about deprecated units.)
provide testconfigs for LVM (old and new style) and LUKS
provide testconfigs for TMPFS