Fixing parameters interface to accept multiple key-value pairs per port.

E.g.,

<parameters>
  <port1>
    key1=valueA
    key2=valueB
  </port1>
  <port2>
    key3=valueC
    key4=valueD
  </port2>
</parameters>
Merge pull request #17 from usnavi/params_fix

Fixing parameters interface to accept multiple key-value pairs per port.