Bug 1313298. Reinstall disable extension of the same version. r=aswan

Enable a disabled addon when user re-installs the same version.

Before this change disabled addons couldn't be enabled back even if user intentionally reinstalls the same version of addon.
Now if user reinstalls the same version - addon will be enabled back.

Differential Revision: https://phabricator.services.mozilla.com/D4435

--HG--
extra : moz-landing-system : lando