Prevent users from skipping pages

[mlonneman]

Users shouldn't be able to skip steps as they progress through the data submission portal. For instance, someone should not be able to submit data without first agreeing to the MarineGEO data policy. This could be done in two ways, or some combination of the two:

1. Track action button values to lock and unlock subsequent steps. Ex. Users would have had to click the button representing agreement with the data policy in order to be able to click the "submit data" button. The "submit data" button in this case would check to see if the value of the data agreement button was greater than 0 (action buttons initialize as 0 and increment by 1 with each click).

2. Prevent users from clicking the names of proceeding tabs. Users may still be able to navigate to pages they've already completed.

[mlonneman]

Went with option 2. Users cannot click the names of tabs in the header and the cursor doesn't change from the regular arrow to a hand. Back buttons have been added to each page.