#30 Include welcome text and trivial app by default

Originally at 2014-10-08T14:31:19Z by Herbert Vojčík closed at 2014-11-25T10:42:43Z As @hhzl mentioned in discussion of #29, a simple app may be generated instead of a blank page. A class can have start method, it may bind a button programmatically in Amber itself and devs could see this is actually an app they may start to change.