Update BaseUnit initialize.

  * Replace `send` method with `instance_variable_set`
    to set instance variables instead of defining methods.
    The previous approach simply overrides the method with
    the contents of each row until it reaches the end of
    the file. This results in all objects having the same
    `first_name`, `last_name` etc.
Merge pull request #2 from jmejia/meta_base_unit

Update BaseUnit initialize to be more meta.