Merge pull request #25 from SunGard-VPM/null-issues

Issue #166: Prevent scientific notation in decimal & floating point serialization
reverted pull 24 that marshalls nil xml values for unspecified fields
Merge pull request #26 from pysimplesoap/revert-pull24

reverted pull 24 that marshalls nil xml values for unspecified fields
Merge remote-tracking branch 'upstream/master'