Add support for nanoseconds and microseconds for Config#getTimeUnit

Change-Id: I0a5828438810dd23790cba52d7ae2e055c6a3fc9
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/ConfigTest.java

 import static java.util.concurrent.TimeUnit.HOURS;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.concurrent.TimeUnit.MINUTES;
+import static java.util.concurrent.TimeUnit.NANOSECONDS;
+import static java.util.concurrent.TimeUnit.MICROSECONDS;
 import static java.util.concurrent.TimeUnit.SECONDS;
 import static org.eclipse.jgit.util.FileUtils.pathToString;
 import static org.junit.Assert.assertArrayEquals;
 
 	@Test
 	public void testTimeUnit() throws ConfigInvalidException {
+		assertEquals(0, parseTime("0", NANOSECONDS));
+		assertEquals(2, parseTime("2ns", NANOSECONDS));
+		assertEquals(200, parseTime("200 nanoseconds", NANOSECONDS));
+
+		assertEquals(0, parseTime("0", MICROSECONDS));
+		assertEquals(2, parseTime("2us", MICROSECONDS));
+		assertEquals(2, parseTime("2000 nanoseconds", MICROSECONDS));
+		assertEquals(200, parseTime("200 microseconds", MICROSECONDS));
+
 		assertEquals(0, parseTime("0", MILLISECONDS));
 		assertEquals(2, parseTime("2ms", MILLISECONDS));
+		assertEquals(2, parseTime("2000microseconds", MILLISECONDS));
 		assertEquals(200, parseTime("200 milliseconds", MILLISECONDS));
 
 		assertEquals(0, parseTime("0s", SECONDS));

org.eclipse.jgit/src/org/eclipse/jgit/lib/DefaultTypedConfigGetter.java

 			inputUnit = wantUnit;
 			inputMul = 1;
 
+		} else if (match(unitName, "ns", "nanoseconds")) { //$NON-NLS-1$ //$NON-NLS-2$
+			inputUnit = TimeUnit.NANOSECONDS;
+			inputMul = 1;
+
+		} else if (match(unitName, "us", "microseconds")) { //$NON-NLS-1$ //$NON-NLS-2$
+			inputUnit = TimeUnit.MICROSECONDS;
+			inputMul = 1;
+
 		} else if (match(unitName, "ms", "milliseconds")) { //$NON-NLS-1$ //$NON-NLS-2$
 			inputUnit = TimeUnit.MILLISECONDS;
 			inputMul = 1;