Add Maven profile to skip build of plugin modules

Building the plugin modules ('Plugin API' and 'Plugin Archetype') may
take a significant amount of time (since many jars are downloaded).
During development it is not needed to build the plugin modules. This
change adds a Maven profile that skips the build of the plugin modules,
so that developers have a faster turnaround. This profile is called
'no-plugins' and it's active by default. To include the plugin modules
into the build activate the 'all' profile:

mvn clean package -P all

The script to make release builds has been adapted to activate the
'all' profile so that the plugin modules are always built for release
builds.

Change-Id: I6c3bd7dfcb80f1bf9d681a660d6fca2707b35f75
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

pom.xml

@@ -88,12 +88,26 @@ limitations under the License.
     <module>gerrit-war</module>
 
     <module>gerrit-extension-api</module>
-    <module>gerrit-plugin-api</module>
-    <module>gerrit-plugin-archetype</module>
 
     <module>gerrit-gwtui</module>
   </modules>
 
+  <profiles>
+    <profile>
+      <id>all</id>
+      <modules>
+        <module>gerrit-plugin-api</module>
+        <module>gerrit-plugin-archetype</module>
+      </modules>
+    </profile>
+    <profile>
+      <activation>
+        <activeByDefault>true</activeByDefault>
+      </activation>
+      <id>no-plugins</id>
+    </profile>
+  </profiles>
+
   <licenses>
     <license>
       <name>Apache License, 2.0</name>