Replace dropwizard.version to project.version

See 3c24c64.

Also Maven has problems with loading the `dropwizard-request-logging`
module when it accessed via a user variable. See #1449.

dropwizard-bom/pom.xml

@@ -779,7 +779,7 @@
             <dependency>
                 <groupId>io.dropwizard</groupId>
                 <artifactId>dropwizard-request-logging</artifactId>
-                <version>${dropwizard.version}</version>
+                <version>${project.version}</version>
             </dependency>
             <dependency>
                 <groupId>io.dropwizard</groupId>