Add configurable word and character limits to questions

[petschekr]

• Admins can now add maxWordCount, minWordCount, maxCharacterCount, and minCharacterCount to fields that accept text
• Character counts use HTML5 form validation for better user experience (and won't allow sending of form until it passes)
• Word counts are represented live to the user as they type
• Word and character counts are checked server side to prevent sneaky users / crappy browsers from allowing bad inputs
• Word and character counts are stackable (can configure multiple limits for the same question)

Closes #268