Bump version to 0.2.0 to reflect feature additions present in the last release

Version 0.1.5 included the following changes and should have had a MINOR version change,
not merely a change in the PATCH version.

* add "node set-provision-state" command
* CLI supports vendor-passthru method
* add "driver-properties" command to expose what "driver_info" attributes
  each driver expects
* client support for the get and set boot device calls on the new management
  interface
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