Use SQLite in development and test environments

It is a good idea to use the same database technology
as production in development and test as well, but we'll
use SQLite for the time being because it's very easy
to setup.
Ensure a successful response is returned when a user exists
Ensure 404 is returned when a user doesn't exist
Let rbenv figure out which ruby version to use
Don't track default SQLite databases through GIT
User bundler to manage dependencies
Create users table
Create User model
Setup environment, logger and db connection for user service
Get users by name