Generate table TodoItems
Create table Categorizations
Create Category table
Establish relationships betw TodoItems and Categories
Change capitalization of <h1>
Change root route to todo_items#index
Update README to include new features
Fix formatting
Conditionally show 'No to-do items' message; fix capitalization on bottom link
Fix capitalization in <h1>
Create User table
Files pertaining to creation of User table
Add belongs_to :user
Add User to list of models in README
Add foreign keys for Categorizations table