Add basic skeleton for User model

Command used to generate this:
  "rails generate model User name:string"
Add To-do list to keep track of things we need
Use relative path when requiring test helper

This allows to run tests directly with ruby from any file path
(ruby test/unit/user_test.rb).

Otherwise one would get following error:
/usr/lib64/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in `require': cannot load such file -- test_helper (LoadError)
	from /usr/lib64/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in `require'
	from user_test.rb:1:in `<main>'
Add gitignore files (db + log) and remove development.log from git
Add tests for user model