Object services user-agent string uses full name

It does not appear that, aside from the user-agent string, the strings
"obj-server", "obj-updater", or "obj-replicator" (or "obj-<anything>"*)
appear in the swift code base, aside from the directory containing the
object services code being named "obj".

Furthermore, the container, account, and proxy services construct their
user-agent string, as reported in the logs, using their full name. In
addition, this full name also shows up as the name of the process via
"ps" or "top", etc., which can make it easier for admins to match log
entries with other tools.

For consistency, we update the object services to use an "object-"
prefix rather than "obj-" in its user agent string.

* obj-etag does appear in a unit test, but not part of the regular
code.

Change-Id: I914fc189514207df2535731eda10cb4b3d30cc6c
Merge "Object services user-agent string uses full name"