clean up package (/usr/LICENSES and /usr/etc)

Move licenses from /usr/LICENSES to /usr/share/licenses/arrayfire.

Remove /usr/etc/arrayfire_version.txt which, according to the following comment from CMakeModules/CPackConfig.cmake, is used only to have a file inside the Debian arrayfire meta package:

# Create a arrayfire component so that Debian package has a top level
# package that installs all the backends. This package needs to have
# some files associated with it so that it doesn't get deleted by
# APT after its installed.

I couldn't find any other references to this file.

added priority3-normal statusunconfirmed labels

assigned to @svenstaro and @kgizdov

Thanks, I fixed this in a slightly different form in rel-7.

closed