Generalized names

So as to accommodate the change from radio inputs to selects as well
Output a <select> and <options> instead of radio buttons
Support forced choices and allow clearing the value when using radios
Add terms inline via AJAX
Update README.md
Make adding new terms inline opt-in
Make 'add new term' functionality opt-in
Formatting
make some formatting/methodology improvements to the classes
Update readme
Merge branch 'jchristopher-master'. Includes ability to use a 'select' element instead of radios, and adds an 'adder' button