Changed project 'completed' to check_box.

Fixes #16
Use customer_id when creating a project, if available.

This will properly set the customer field when you navigate to /customers/:id/projects/new
Changed date fields to date_select
Added select field for status
Add a modal for changing the status of a project
Made the code less duplicated and easier to read
Made the status dialog a little nicer to look at (not by much).

Closes #12
Merge pull request #25 from matthew-parlette/project_field_enhancements

Project field enhancements