Fix the JSONRPC read service issue

Fix the JSONRPC read service issue

The steps to upgrade pip and install pyzmq & zmq were failing
because it's done with an old version of OS default pip.

Add a new keyword to support Python 3 virtual environment in
SSHKeywords.robot, and start the read service in a new Python 3
virtual environment created with the new keyword - a new keyword
was created, instead of updating the existing keyword, in order
not to interfere with other test cases.

Replace 'send' with 'send_string' in the odl-jsonrpc-test-read
Python script because the former cannot be used to send a unicode
string in Python 3.

And remove new lines & spaces from the configuration data when
creating the script command to make it a little simpler.

Signed-off-by: Sangwook Ha <sangwook.ha@verizon.com>
Change-Id: I70e694bb1a4fa21c2133b262e291791e6afe5ce8