client: separate global options from multiple servers

client: separate global options from multiple servers

In a single client invocation, currently all global options from all
servers accumulate in a single global options dictionary. This is fine
if the invocation creates only a single server session, but when a
client connects to multiple servers, this is a mess because there is no
way to assign different global options to different jobs.

This patch instead creates a global options array when a client creates
multiple server sessions. Each array element contains the global options
for a different server session and is identified by the hostname and
port. When the client connects to only a single server, the global
options object remains a dictionary in order to maintain backward
compatibility.

Signed-off-by: Vincent Fu <vincent.fu@samsung.com>