pom: add headless=true for zoo, splice, & spliceFast profiles
pom: add headless=true for zoo, splice, & spliceFast profiles

Addresses fact that as of java 1.6.0_51 on OS X, (some?) java processes
appear as applications in the dock.

splicemachine/spliceengine,CompilerWorks/spliceengine,splicemachine/spliceengine,CompilerWorks/spliceengine,CompilerWorks/spliceengine,CompilerWorks/spliceengine,CompilerWorks/spliceengine,splicemachine/spliceengine,splicemachine/spliceengine,CompilerWorks/spliceengine,splicemachine/spliceengine,splicemachine/spliceengine,splicemachine/spliceengine