Keep a minimum number of sync session logs on the client, for future use in stats display.

Currently, when a distributed server syncs with the central server, the central server keeps a SyncSession log of activity; the distributed server deletes its own, and instead keeps a chronograph record.

In this change, I:
* Allow some number of SyncSession logs to persist on the distributed server, configurable through a settings constant.
* Turned on "strip trailing whitespace" on my editor; most changes in this pull request are stripped whitespace.

How I tested:
* Ran securesync
* Viewed the results using tools from an upcoming pull request

Note:
* Chronograph keeps a full log, which can be quite weighty (running once an hour, contains text-based results).  To avoid database bloat, we may want to force chronograph to use this type of rolling log.  Thoughts?