api_check_ipa_version: Fix version comparison for more than one digit

The fallback function used to compare IPA versions was spliting the
version string into a tuple of strings, and the comparison of the tuple
would fail if comparing a field with one digit aginst a two-digit one,
for example, '8' with '10', as the string comparison would put '10'
before the '8'.

This patch forces the version fields to be converted to integers, so
a numerical comparison will be performed. If a version string field
cannot be converted to a number, than the string comparison will still
be used.