New Label form improvements

[erictncabramson]

User Story As a user, I want it to be clear how to make new labels, so that I can easily customize my project!

Acceptance Criteria:

• Hide "New Label" button after it is selected (because it is confusing to have both that button and the Save button)
• Question: Why would we have Enable when making a new label? Is it just because the Edit Label and Add Label forms are the same?