Fixed EnemyOnly target handler

Fixed a bug where in duel player couldn't use debuffs such as Surrender
to Fire against enemy, with or without ctrl key pressed.
Fixed a bug that didn't allow to use debuff in Olympiad when opposing
side was Clan or Alliance mate.

Skills using this target handler cannot be used in party members,
regardless of being in PvP area.

Skills using this target handler can be used in Clan mates while inside
PvP area.

Guessed that unless in PvP area skills using this target handler cannot
be used in Alliance or Command Channel members.

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Unit tests:
Each target case is properly documented using a single unit test.
Added 100% coverage unit tests for this target handler.
Replaced Mockito with EasyMock.