Multiple improvements

Added/improved:

• Twitter handle validaiton. commit-8c530c0
• Validation error helper text will show up when user is typing instead of after clicking "Next" button and will disappear when the validation is passed. commit-da2e68b
• Checkbox - "Same as Member Rep" related logic improvements. Overall smoother and more reliable. commit-da2e68b
• The page will scroll to top automatically when it shows up (so that users don't need to scroll manually). commit-eb87834
• Fixed can't go to next step in React Only mode. commit-6ef3bd6