[Tails-l10n] [review] (de) trust page translation

Hi,

please review
https://gitorious.org/flapflap/tailsxlat.git
branch de-trust

Commits:
179baf7 some more minor fixes
112a3af more fixes
8495358 fix typos and improve language

The original text seems to have been written in a hurry, so I tried to
fix and improve it. The base already was quite good though.

~flapflap