Implement the SeaMicro Power driver

* Implement ironic's PowerInterface for SeaMicro power driver
* Use python-seamicroclient to access SeaMicro hardware
* Adds unit tests for SeaMicro power driver
* Adds python-seamicroclient to requirments.txt

Change-Id: I4b7263a28d479faebe1969f3d622bbb1f9957897
Implements: blueprint seamicro-power-driver
Merge "Implement the SeaMicro Power driver"