unable to set multiple same headers per action message

[dafik]

eg. OriginateAction https://wiki.asterisk.org/wiki/display/AST/Asterisk+13+ManagerAction_Originate

allow multiple Variable
"Variable - Channel variable to set, multiple Variable: headers are allowed."

i think that objToRaw from asterisk-ami-event-utils should:
check for array type or
provide method to set custom serialization on action Object

[dafik]

AmiConnection.write allow message as string but,
AmiClient.action (and write,send) not
if (!message.ActionID) { message.ActionID = this._genActionId(this._specPrefix); }

[jaunis]

I submitted a pull request for this: #9