Bump up version number to 2.15.0

Author: michel-kraemer

README.md

@@ -31,7 +31,7 @@ You may also use [Maven](http://maven.apache.org/) to download bson4jackson:
     <dependency>
         <groupId>de.undercouch</groupId>
         <artifactId>bson4jackson</artifactId>
-        <version>2.13.1</version>
+        <version>2.15.0</version>
     </dependency>
 </dependencies>
 ```
@@ -41,7 +41,7 @@ following snippet to your `build.gradle`:
 
 ```gradle
 dependencies {
-    implementation 'de.undercouch:bson4jackson:2.13.1'
+    implementation 'de.undercouch:bson4jackson:2.15.0'
 }
 ```
 

build.gradle

@@ -7,7 +7,7 @@ apply plugin: 'maven-publish'
 apply plugin: 'signing'
 apply plugin: 'java'
 
-version = '2.13.2-SNAPSHOT'
+version = '2.15.0'
 group = 'de.undercouch'
 sourceCompatibility = '1.8'
 targetCompatibility = '1.8'