Very first draft for XML schema definition file.
Changes proposed by hanno
if no value is set, no errors can be set

Now, there are nor errorminus, errorplus, if no value is submitted
corrected error bars for temperature stated in http://arxiv.org/pdf/1401.6811v1.pdf
Corrected DE Format
Removed error bars with value 0
Current version

Only 2 of 1092 xml files are recognized with a not accepted format
corrected RA/DE; (coords published are not correct)

information from M. Cappetta:
please use the following SDSS link for the identification of WTS-1.

http://cas.sdss.org/astrodr7/en/tools/explore/obj.asp?id=758879745081674546
Errata corrige is still on the way of publication.
Merge pull request #291 from Sol-d/2014-07-23

First draft of an XML Schema Definition.