make limit [optionally]for user invites

[artman325]

add optionally params:
inviteLimit
inviteDuration

so person can limit to invite people in the community. if limit exceed throw message in invitePrepare methods

[EGreg]

Same technique as SalesContract

[EGreg]

Factory.produce() and initialization()

If inviteDuration = 0 that means no limits!
If inviteLimit = 0 then no one can invite.