[Platform] Memory Meter hidden when MCT initially loads

This pull request addresses issue #124.

The memory meter (located at the bottom right of the screen) is now hidden when MCT is started-up (and remains
hidden wrt all windows till the user changes the visibility under the 'help->Memory Usage Monitor' menu option).

Wrote or re-wrote unit tests (Y/N): N
 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 via pull-request
 Describe potential impact on other areas of the code: None
 Describe any test prerequisites for this fix (e.g., restart the database): None
 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