SUPEE-3941 - Addresses extension-related issues

This is an official Magento patch.

* When you install a community-created translation package,
the translation provided by the package overwrites any existing
translations for the same items. This enables you to more easily
install packages with translations.

* To improve security, Magento Connect now uses HTTPS by default
to download extensions, rather than FTP.

* Extension developers can now create an extensions with a dash
character in the name. Merchants can install those extensions without issues.

* Magento administrators who attempt to install an extension
with insufficient file system privileges are now informed.
Typically, the Magento Admin Panel runs as the web server user.
If this user has insufficient privileges to the your Magento
install dir/app/code/community directory structure, the Magento
administrator sees an error message in the Magento Connect Manager.
To set file system permissions appropriately, see
http://www.magentocommerce.com/knowledge-base/entry/install-privs-after#extensions
Merge pull request #3 from macopedia/SUPEE-3941

SUPEE-3941 - Addresses extension-related issues