add pluginManagement for gfnexus-maven-plugin, to automate interactions with maven.java.net.
	PS2: remove trailing spaces in gfnexus-maven-plugin configuration

Change-Id: Ibf51b578850434fae883de50c8027bf2440cabd6
Merge "add pluginManagement for gfnexus-maven-plugin, to automate interactions with maven.java.net. 	PS2: remove trailing spaces in gfnexus-maven-plugin configuration"