LPS-47374 Add content targeting to plugins includes

Hey Brian,

Following your idea in brianchandotcom/liferay-plugins/pull/3301 we've added apps/content-targeting to the plugins.includes.path of the build.xml in the 6.2.x plugins SDK. 

Now if a developer adds the list of Content Targeting plugins to his build.<name>.properties file, they will be deployed.

Thanks

@juliocamarero