devtool: add: use the appropriate file naming and versioning for SCM recipes

devtool: add: use the appropriate file naming and versioning for SCM recipes

* Recipes that fetch from git, svn or hg by OpenEmbedded convention
  should normally be named with this as a suffix, since PV is meant to
  be set appropriately within the recipe, so follow this. In order to
  make this work we need to be able to have the version independent from
  the file name, so add a -V option to recipetool create to allow this
  to be specified.
* If -V is specified on the devtool add command line, ensure at PV gets
  set to include this version.

(From OE-Core rev: 2b997c41c6476a13bf516586d56a9051aceb93ec)

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