fix junit deprecations, issue #339

...it/net/i2p/client/naming/SingleFileNamingServiceTest.java

...java/test/junit/net/i2p/crypto/eddsa/EdDSAEngineTest.java

core/java/test/junit/net/i2p/crypto/eddsa/UtilsTest.java

...t/net/i2p/crypto/eddsa/math/AbstractFieldElementTest.java

...a/test/junit/net/i2p/crypto/eddsa/math/ConstantsTest.java

...est/junit/net/i2p/crypto/eddsa/math/GroupElementTest.java

.../java/test/junit/net/i2p/crypto/eddsa/math/MathUtils.java

.../crypto/eddsa/math/bigint/BigIntegerFieldElementTest.java

...i2p/crypto/eddsa/math/bigint/BigIntegerScalarOpsTest.java

...2p/crypto/eddsa/math/ed25519/Ed25519FieldElementTest.java

...o/eddsa/math/ed25519/Ed25519LittleEndianEncodingTest.java

...t/i2p/crypto/eddsa/math/ed25519/Ed25519ScalarOpsTest.java

...it/net/i2p/crypto/eddsa/spec/EdDSAPrivateKeySpecTest.java

core/java/test/junit/net/i2p/data/DataStructureImplTest.java

core/java/test/junit/net/i2p/data/KeyCertificateTest.java

core/java/test/junit/net/i2p/data/LeaseSetTest.java

core/java/test/junit/net/i2p/data/LeaseTest.java

core/java/test/junit/net/i2p/data/PrivateKeyTest.java

core/java/test/junit/net/i2p/data/PublicKeyTest.java

core/java/test/junit/net/i2p/data/SigningPrivateKeyTest.java