Clean up ScreenTest & upgrade EasyMock.

Upgrade EasyMock dependency in main pom.xml to version 3.1.

Change EasyMock imports from package org.easymock.classextension.* to
org.easymock.*, since the classextension package is deprecated; i.e.,
the functionality has been merged into standard EasyMock in version 3.1.

When stubReturn-ing the getMsTime() method on the TimeProvider mock,
specify the return value as 0L to satisfy the compiler, since it needs
to return a long, rather than casting the 0 to a long, since it's more
elegant.