tests: resetGlobalIoService for every test

All tests must use BaseFixture or a fixture derived from it to get this feature.

This commit also fixes a few warnings in tests/mgmt, and moves test cases into nfd::tests namespace.

refs #1290

Change-Id: I891441a5abce170e35648d463f7157b18429f79f
diff --git a/tests/core/event-emitter.cpp b/tests/core/event-emitter.cpp
index c44b6d2..b6ee048 100644
--- a/tests/core/event-emitter.cpp
+++ b/tests/core/event-emitter.cpp
@@ -6,9 +6,12 @@
 
 #include "core/event-emitter.hpp"
 
-#include <boost/test/unit_test.hpp>
+#include "tests/test-common.hpp"
 
 namespace nfd {
+namespace tests {
+
+BOOST_FIXTURE_TEST_SUITE(UtilEventEmitter, BaseFixture)
 
 class EventEmitterTester : noncopyable
 {
@@ -117,8 +120,6 @@
 EventEmitterTest_RefObject_byRef(const EventEmitterTest_RefObject& a1) {}
 
 
-BOOST_AUTO_TEST_SUITE(UtilEventEmitter)
-
 BOOST_AUTO_TEST_CASE(ZeroListener)
 {
   EventEmitter<> ee;
@@ -228,4 +229,5 @@
 
 BOOST_AUTO_TEST_SUITE_END()
 
+} // namespace tests
 } // namespace nfd