Add support for specifying client-side epemeral port

-e/--cport now allows a user to specify the client-side port
used for data transfer.

Signed-off-by: Kevin Constantine <kevin.constantine@gmail.com>
specify client-side port:  Only support --cport

Remove support for short-option -e

Signed-off-by: Kevin Constantine <kevin.constantine@gmail.com>
specify client-side port: UDP support

--cport can be specified for udp connections

Signed-off-by: Kevin Constantine <kevin.constantine@gmail.com>
Merge branch 'master' of github.com:kevinconstantine/iperf into kevinconstantine-master
Minor documentation updates for new --cport option.

For #207.
Merge branch 'kevinconstantine-master'