Maven: use same version number for plugin version and API version

Using plugin version 0.1 means the version is the same regardless of
which branch the plugin is built from.

Change it to make the plugin version the same as the API version
used to build it.

Change-Id: Ib257661d91079da83a619ca716e0d1c32fe16813
diff --git a/pom.xml b/pom.xml
index 7ec228b..d30c292 100644
--- a/pom.xml
+++ b/pom.xml
@@ -22,10 +22,10 @@
   <groupId>com.googlesource.gerrit.plugins</groupId>
   <artifactId>cookbook-plugin</artifactId>
   <packaging>jar</packaging>
-  <version>0.1</version>
+  <version>2.10</version>
   <properties>
     <Gerrit-ApiType>plugin</Gerrit-ApiType>
-    <Gerrit-ApiVersion>2.10</Gerrit-ApiVersion>
+    <Gerrit-ApiVersion>${project.version}</Gerrit-ApiVersion>
   </properties>
 
   <build>