jsonrpc: Use asyncore instead of custom solution

Use the built in asynchronous loop infrastructure instead of a custom
one. This is much less code to maintain.

I purposefully changed dumped the tcpReactor name for the class and
module because I will do some more work to add unix sockets in the
future.

If only someone would have told me this existed beforehand. I wouldn't
have spent so much time on the original reactor. Anyway, no use crying
over spilt milk.

Change-Id: I6e07a125eb905357f130d460accbc67c4b9a66ed
Signed-off-by: Saggi Mizrahi <smizrahi@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/11605
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Tested-by: Dan Kenigsberg <danken@redhat.com>