recipetool: create: fix picking up name from local python source tree

recipetool: create: fix picking up name from local python source tree

Make use of the extravalues dict to send back other variable values from
the python handling plugin, and enable passing back PV and PN. This not
only places variable values in the final recipe a bit more consistently
with other types of source, it also allows the name and version to be
picked up fron a local source tree and not just when the recipe is
fetched from a remote URL that happens to have those in it.

(From OE-Core rev: 3e7029f28c6ea9bb1d283bcdc3fdfee11455af8e)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>