Correct Signficance rendering on Control info page.

Per [69914488](https://www.pivotaltracker.com/story/show/69914488).  Related to modal fix on [PR 1265](https://github.com/reciprocity/ggrc-core/pull/1265).

Info page also had the incorrect mapping (0 -> Key, 1 -> Non-Key) as in PR 1265.  Now fixed.