Add support to dynamically upload drivers in PLUMgrid plugin

PLUMgrid plugin will be able to dynamycally upload any of its available drivers.
It will simplify any CI testing by changing the configuration file for the plugin
instead of changing the code directly.

Change-Id: I56da881688cfdf8f9a1b655c1080c39ffc0133a5
Closes-bug: #1315137
Merge "Add support to dynamically upload drivers in PLUMgrid plugin"