C1 khloud c3 s3 register as developer

[Issue #85]

UML reviewer: @Mirna-Yacout 
code reviewer: @adamggg 
documentation reviewer: @zoheiry 
scenario reviewer: @KareemAliRahman 
test reviewer: @zoheiry 

files changed concerning story: 
models/developer.rb
controllers/developer_controller.rb
views/developer/new.html.rb