TzTraffic: retry failed injections

Tztraffic injects operations naively from one network to the other. As both networks may behave differently and propagation/bloc times might impact operation inclusion, some operation might fail to be included in the target network. To maximize the chances of inclusion, we need to be able to retry (indefinitely ? for a fixed number of blocks ?) any operation we failed to include.

To begin we can simply store failed operations and retry them indefinitely (this may quickly become big if we cannot discriminate between failures because of network behavior and because of unimplemented operation translations in tztraffic). A follow-up effort could be to parameterized this.