Merge pull request #1 from fronx/master

always use percentage for humidity
added first event listeners and read some entered values
added parseFloat to user-inputted values and cleaned up event listener code
minor html formatting changes
add handler for radio buttons, started CSS
solution divs appear/disappear for appropriate radio button selections. added event listeners for other equations but left commented out for now.
solution appears in HTML for humidity only, altered event listeners to do this
fixed it so now all 3 equations display answers
starting to mess with CSS, round numbers to the nearest hundredth, trying to validate some fields
fixed parentheses problems from adding parseFloat and toFixed
fixed tests so they round appropriately, moved rounding of answers to another less cluttered place
just black and white now, trying to figure out how to default check radio button and to make NaN not appear... everything else is working
solutions only display if their answer is a number (and not NaN)
reduce specificity