i18n: Add first wizard screen in german
i18n: Add german translation of config screen

While the english translation was used as reference, sometimes
the french file was used as complementary reference too.
boot.conf: Fix erroneous labels of user display name

Display name tells us what it actually is and
the french translation already makes use of this
terminology.
boot.conf: Improve display name use more consistent

- In french Nom d'affichage is already used for the admin
  login, make it the same for regular users.
- Small precision in german translation
- Adjust the english description, the display name
  is the name shown to users, unrelated to user-friendlyness
- Finally: Adapter the label for the description modifed so
  it matches the actual english definition everywhere.
boot.conf: Introduce tooltip for Mail address

- Originally missing the tooltip was actually from the display name
- Tries to reflect gender-neutral usage for german and french, in english
  not required
- Reuses Email in french as used in pydio, although there are various
  more or less official definitions in french.
boot.conf: Connexion -> Connection

Possibly a "french-ism", although connexion exists in british
(Oxford) english, american english doesn't use this term. I've
never seen a english program using the british variant, sorry Brits. ;-)
boot.conf: Terminology for configuration store

Although many sets of configuration(s) make up the whole
Pydio configuration, I guess we can speak about having one
(large) set of configuration data to rule them all, thus similar
to other applications we have a singular configuration storage.
boot.conf: Proposed improvement on user guidance

In first instance admins should be made aware of what makes
the difference in using a DBMS as config storage or a serialized
file.

At this stage they are not/less interested in knowing what type of DBMS,
only when they want to go with a DBMS, let them chose from the list of
DBMS supported by Pydio.
Merge pull request #590 from matsimon/german-i18n-boot.conf

German i18n boot.conf
Seems ok to me, thanks for the "x" of connection :-)