Revert "Remove PowerMock"

This reverts commit c7008751f32a64b53bc4653f01e29b977d92d001.
Change Mockito dependency to core instead of all
Execute Gradle builder from Eclipse less often

-Should fix error messages appearing so often
Fix for intermittent test

-Test is testGetIterationForDate_twoIterations
-I believe it was due to Java deciding an arbitrary value for
milliseconds previously.
Remove PowerMock from TestPostBoardEntityManager

-There is still one possible time zone based intermittent
Remove refreshing from Gradle builder in Eclipse

-Was unnecessary and should help stability in Eclipse, especially on
slower machines
Fix issues with timezone in TestPostBoardEntityManager
Add TestResponse
Add TestNetwork
Rename initNetwork to setInstance in Network

-Name is more accurate of what it actually is doing
Finally fix the error pop-up in Eclipse

-Harmless but annoying pop up when doing Clean and Build Workspace
Remove PowerMock from TestAddMessageRequestObserver
Increase code coverage in BoardPanel
Exclude unit tests from JaCoCo code coverage report
Remove PowerMock from TestAddMessageController
Remove PowerMock from TestPostBoardMessage
Improve code coverage for PostBoardMessage

100%
Move PowerMock dependency to sub-projects
Remove PowerMock from TestGetMessagesController

-100% Code Coverage
Remove PowerMock from TestGetMessagesRequestObserver

-PostBoard now free of PowerMock