Merge pull request #21 from stdweird/remove_SL4_support

Remove SL4 support by fixing the parted units to use MB
allow to specify a filesystem type to be checked
fix pod
more strict regexps
tests for has_filesystem
formatfs tests
add tests with create_if_needed (factored out the is_create_needed part)
also fix bug with regex in has_filesystem
fix last fail also (wrong file input)