scripts/combo-layer: make init set up initial component data

scripts/combo-layer: make init set up initial component data

The "init" subcommand will now copy the current state of each component
repository into the combo layer repository, set last_revision for each
component, and then use "git add" to set up the initial commit (but will
not actually make the initial commit - that is left up to the user).
Also take the opportunity to bump the version number.

(From OE-Core rev: d4d491aa118b6cbe895167c62a46d883abc7b4ab)

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