The 2 reasons are :
- creation of user fail if name is empty : in after_save, it tries to create a
namespace with namespace.name = user.name and namespece validates presence
Namespace#name
- in the web app links to team members are broken with empty User#name because
they are of the form <a href'...'> user.name </a>

Merge branch 'master' into non-interactive-aws-install

Conflicts:
	doc/installation.md

Fix merge mess in installation.md

Didn't bother with files in db/, config/, or features/

Gitlab requires an email address for all user accounts as this is the
default account id and is used for sending notifications. LDAP accounts
may be missing email fields so handle this by showing a sensible error
message before redirecting to the login screen again.

Resolves github issue #899
Signed-off-by: NPat Thoyts <patthoyts@users.sourceforge.net>