Bug 1013510 - Uplift Add-on SDK to Firefox r=me

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rename : addon-sdk/source/python-lib/cuddlefish/tests/preferences-files/packages/curly-id/package.json => addon-sdk/source/test/fixtures/preferences/curly-id/package.json
rename : addon-sdk/source/python-lib/cuddlefish/tests/preferences-files/packages/no-prefs/package.json => addon-sdk/source/test/fixtures/preferences/no-prefs/package.json
rename : addon-sdk/source/python-lib/cuddlefish/tests/preferences-files/packages/preferences-branch/package.json => addon-sdk/source/test/fixtures/preferences/preferences-branch/package.json