Update branding to µPaaS by @sneak

Change all references from "upaas" to "µPaaS" in page titles,
headers, and README. Add attribution link to sneak.berlin in
the navigation bar.

templates/app_edit.html

@@ -1,6 +1,6 @@
 {{template "base" .}}
 
-{{define "title"}}Edit {{.App.Name}} - upaas{{end}}
+{{define "title"}}Edit {{.App.Name}} - µPaaS{{end}}
 
 {{define "content"}}
 {{template "nav" .}}