'Perform Analysis' button should stay inactive (light purple) until all the needed items are provided

[monajalal]

For example, in the case of choosing other as issue, the button should stay inactive until the user has provided all the following:

1. A set of examples/samples to be annotated in Section 1
2. Issue name (input box in front of 'Other')
3. Comma-separated frame names (input box under 'Other')
4. User's email

Only after all the 4 requirements for this case or (other requirements for the other case where the use chooses one of our own policy issues), the 'perform analysis' button should turn our 'dark purple'.