Added German Translations (#406)

* Added German Translations

Translated using
https://docs.djangoproject.com/en/1.9/topics/i18n/translation/

Added language drop down menu's for base.html, registration & login
pages

Known issues:
* Translated items in whtracker>create signature remain translated when
posted
* No date/time localisation for Fleet/Structure timers

* Added time locale

Added date/time locale to
*Structure Timers
*Fleet Timers
*Fleet timer form datetimepicker.js

Fixed a bug where the bootstrap label didn't show up when making a
structure timer using the translated form

Missed some base.html translations

* Small translation error

Some obscure SRP strings went unnoticed for context review

* FAT & Fleet-up German Translations

+ a fix in settings.py.example

The only small thing not done is German Date/Time locale for Fleet-up

* Compiled de/django.po

stock/templates/registration/password_reset_complete.html

@@ -51,7 +51,7 @@
                 <p class="text-center">{% trans "Your password has been set." %}</p>
 
                 <a href="{{ login_url }}">
-                    <button class="btn btn-lg btn-success btn-block">Log In</button>
+                    <button class="btn btn-lg btn-success btn-block">{% trans "Login" %}</button>
                 </a>
             </div>
         </div>