[NOP] removed dead code

The ProjectExhangeInfoDataObject class is no longer used
since commit b9ba240645b71c730f10bd63c43f8f5c8edf2431.

Change-Id: Idfe4f7e7afd4f92f03417466863690824d9ac999
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/917
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>
[PERFORMANCE] reduced network usage for activities

Removed the TimedActivities* classes from the
serialization process.

Reduced the amount of data send. The JID is already
included in the PacketExtension and the sequence numbers
can be easily recalculated and so just sending the start sequence
number is more than enough.

Change-Id: Ic76b3a4ef4db25a6f4e52fb491b45c620e750d66
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/916
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>