Add support for attachments
Add support for attachments

jettisonjoe/openhtf,fahhem/openhtf,google/openhtf,fahhem/openhtf,amyxchen/openhtf,ShaperTools/openhtf,grybmadsci/openhtf,grybmadsci/openhtf,jettisonjoe/openhtf,grybmadsci/openhtf,google/openhtf,jettisonjoe/openhtf,google/openhtf,ShaperTools/openhtf,grybmadsci/openhtf,fahhem/openhtf,amyxchen/openhtf,ShaperTools/openhtf,google/openhtf,ShaperTools/openhtf,fahhem/openhtf,ShaperTools/openhtf,jettisonjoe/openhtf