Added sendgrid ip pool capability#29

Open

vladshub wants to merge 3 commits intostephenb:masterfrom

YotpoLtd:master

Commits on Apr 5, 2017

sendgrid pool header support

Micha Zana
authored and
Vladislav Shub
committed
concacenate category

Micha Zana
authored and
Vladislav Shub
committed
concatenate category when no array exists

Micha Zana
authored and
Vladislav Shub
committed