Added additional permission to the license under GPLv3 section 7

"The copyright holders grant you an additional permission under Section 7 of
the GNU General Public License, version 3, exempting you from the requirement
in Section 6 of the GNU General Public License, version 3, to accompany
Corresponding Source with Installation Information for the Program or any work
based on the Program. You are still required to comply with all other Section 6
requirements to provide Corresponding Source."

Section 7 of GPLv3 allows copyright holders to issue additional permissions
and this specific additional permission is compliant with the said section 7.
The language for this additional permission has been written according to the
requirements of GPLv3. We believe this additional permission enables wider use
of Canola2 in different kind of business models and product offerings,
especially in CE devices. This additional permission combines the best parts
of GPLv2 and GPLv3 experiences. We encourage other projects to consider use of
this additional permission if they have similar needs.

Signed-off-by: Eduardo Lima (Etrunko) <eduardo.lima@openbossa.org>

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