added draft nbt_db object

@ssimpraga @regg33 what do you think?
Expanding a bit the object draft
add age and Gender
Made the initial folders for the new objects..

@ssimpraga @regg33
Expanded the objects a bit more..
Initial version of Objects closes #50
close #46 Group definition should now work.
close #46 everything should now work until nbt_selectbiomarkers
made NBTelement default database
closes #49 nbt_selectbiomarkers not needed
remove nbt_selectbiomarkers
Merge branch 'master' into NewDataLayer
small error
Added multiple draft objects
Merge branch 'NewDataLayer' of https://github.com/NeurophysiologicalBiomarkerToolbox/NBT into NewDataLayer
Merge pull request #66 from NeurophysiologicalBiomarkerToolbox/master

merge changes in master
started implementing Study object in nbt_selectRunStatistics
starting to implement new SubjectInfo in Group object
nbt_convertInfoFiles now works
New format of biomarkers should work

including conversion of biomarkers