Update BUILD.md
Update BUILD.md

Updated ZIP build command to include MAVEN_OPTS.
anthcp/cdap,mpouttuclarke/cdap,anthcp/cdap,mpouttuclarke/cdap,chtyim/cdap,caskdata/cdap,chtyim/cdap,hsaputra/cdap,chtyim/cdap,chtyim/cdap,mpouttuclarke/cdap,chtyim/cdap,anthcp/cdap,hsaputra/cdap,anthcp/cdap,anthcp/cdap,hsaputra/cdap,caskdata/cdap,chtyim/cdap,hsaputra/cdap,mpouttuclarke/cdap,caskdata/cdap,caskdata/cdap,caskdata/cdap,hsaputra/cdap,mpouttuclarke/cdap,caskdata/cdap