Introduces New Installation Page

If there are no users signed up and no conferences we show a page
informing people what they need to do.

app/views/conferences/_new_install.html.haml

@@ -0,0 +1,21 @@
+.row
+  .col-md-12
+    .well
+      %h1
+        Welcome to your new
+        = link_to('https://osem.io') do
+          Open Source Event Manager
+        installation!
+      %p
+        The first user to
+        - if ENV['OSEM_ICHAIN_ENABLED'] == 'true'
+          = link_to(new_ichain_registration_path('user')) do
+            sign up
+        - else
+          = link_to(new_registration_path('user')) do
+            sign up
+        will the be administrator of it.
+      %p
+        We hope you enjoy using OSEM, if you have any question don't hesitate to
+        = link_to('http://osem.io/#contact') do
+          contact us!