Upgrade jackson deps from 2.4.2 to 2.9.7 (#33)

to get patches for vulns

* CVE-2017-17485 https://nvd.nist.gov/vuln/detail/CVE-2017-17485
* CVE-2018-7489 https://nvd.nist.gov/vuln/detail/CVE-2018-7489
* CVE-2017-7525 https://nvd.nist.gov/vuln/detail/CVE-2017-7525

jackson/src/test/java/com/spotify/hamcrest/jackson/IsJsonNumberTest.java

@@ -31,6 +31,8 @@
 import static org.junit.Assert.assertThat;
 
 import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.BigIntegerNode;
+import com.fasterxml.jackson.databind.node.DecimalNode;
 import com.fasterxml.jackson.databind.node.JsonNodeFactory;
 import java.math.BigDecimal;
 import java.math.BigInteger;
@@ -65,7 +67,7 @@ public void testLiteralLong() throws Exception {
 
   @Test
   public void testLiteralBigInteger() throws Exception {
-    final Matcher<JsonNode> sut = jsonNumber(NF.numberNode(BigInteger.ONE));
+    final Matcher<JsonNode> sut = jsonNumber(BigIntegerNode.valueOf(BigInteger.ONE));
 
     assertThat(NF.numberNode(BigInteger.ONE), is(sut));
   }
@@ -86,7 +88,7 @@ public void testLiteralDouble() throws Exception {
 
   @Test
   public void testLiteralBigDecimal() throws Exception {
-    final Matcher<JsonNode> sut = jsonNumber(NF.numberNode(BigDecimal.ONE));
+    final Matcher<JsonNode> sut = jsonNumber(DecimalNode.valueOf(BigDecimal.ONE));
 
     assertThat(NF.numberNode(BigDecimal.ONE), is(sut));
   }

pom.xml

@@ -63,12 +63,12 @@
       <dependency>
         <groupId>com.fasterxml.jackson.core</groupId>
         <artifactId>jackson-core</artifactId>
-        <version>2.4.2</version>
+        <version>2.9.7</version>
       </dependency>
       <dependency>
         <groupId>com.fasterxml.jackson.core</groupId>
         <artifactId>jackson-databind</artifactId>
-        <version>2.4.2</version>
+        <version>2.9.7</version>
       </dependency>
       <dependency>
         <groupId>com.google.auto.value</groupId>