[Refresh] Add "Refresh Now" action and menu item

Supports nasa/mct#138 by adding Refresh Now menu item. Other menu items have not been added yet for reasons documented in that issue

Additionally, a non-deterministic test failure in plot was uncovered (likely triggered by timing / test ordering changes), and is fixed along with this pull request to avoid failures in continuous build. 

 Wrote or re-wrote unit tests (Y/N): Y
 Ran entire suite of unit tests successfully (Y/N): Y
 Verified bug fix with the described replication steps or verified the implementation meets the requirement cited (Y/N): Y
 Code coverage requirements satisfied (new code=80%, changed code=at least as high as existing) (Y/N): Y
 Code review date and attendees: Code review by pull request
 Describe potential impact on other areas of the code: Center pane views
 Describe any test prerequisites for this fix (e.g., restart the database): N/A
 For bugs marked "Regression - Yes", describe the cause of the regression: N/A
 Did you modify any pom.xml file? If yes, did you thoroughly document your changes and reasons? N