[entropy.tools] pass prefix= to every const_mkstemp call
[entropy.tools] generate_entropy_delta: make sure not to leak any fds
[entropy.client] refactor NoticeBoard Entropy Client API
[entropy.client] move LoadersMixin back into the Client class
[client] update translations
[Rigo] update translations
[server] update translations
Release Entropy 270
Tagging Entropy version 270
[todo] update TODO
[entropy] prefix package download URLs with the category directory

This makes possible to avoid directory hot spots on repository mirrors.
This commit requires some mileage and real-world testing, but it
seems to be running good on a relatively small repository.
No backward compatibility issues have been reported.
[entropy.tools] dump_entropy_metadata: follow symlinks when determining file size

The package file passed as input might be pointing to a symlink.
If we use lstat().st_size we will get the symlink file size back
rather than the source file size, which is of course unwanted.

This is part of the fixes for bug 4604.
[entropy.client.package] Do not alter repository package file directory permissions

It was observed that the new locking mechanism introduced a problem
with the management of repository package files (.tbz2 files passed
to "equo install", for instance). Try to avoid that by symlinking
the package file to a safe location and using this one as pkgpath.

This fixes bug 4604.
Merge remote-tracking branch 'upstream/master'