Adds AddList to Actions

[aom]

NetSuite supports AddList operation so this'll add it into the gem.

You could do same with UpsertList with the exception that if you're using externalId's you will possibly mutate existing records. AddList will throw duplicate error instead.

I took the liberty to update NetSuite version numbers in fixtures related to this new spec.

[iloveitaly]

@aom Thanks for the contribution! Apologies for the delayed response. Left a comment on the PR, otherwise this looks awesome.

[aom]

@iloveitaly rebased this branch as well to resolve conflicts