bugfix: Provider and Description should not appear as Comments

 can't finish this one:
 1) Sample can't have Provider Attribute by MAGE-TAB spec 1.1
 2) Limpopo MAGE-TAB Parser library don't write description attribute value to the output file (patch is needed)
bugfix: Provider and Description should not appear as Comments
Making SDRF generate Source Node instead of Sample as discussed with the team. (Note: By MAGE-TAB spec v1.1 Source Node has 'provider' attribute, but sample node doesn't)
Merge remote-tracking branch 'origin/sampleDescription' into submissionEditor