removed level db option and added if unset to singlenode main
removed level db option and added if unset to singlenode main

mpouttuclarke/cdap,hsaputra/cdap,mpouttuclarke/cdap,chtyim/cdap,caskdata/cdap,mpouttuclarke/cdap,mpouttuclarke/cdap,mpouttuclarke/cdap,anthcp/cdap,caskdata/cdap,chtyim/cdap,anthcp/cdap,anthcp/cdap,caskdata/cdap,chtyim/cdap,caskdata/cdap,anthcp/cdap,hsaputra/cdap,chtyim/cdap,hsaputra/cdap,caskdata/cdap,hsaputra/cdap,caskdata/cdap,anthcp/cdap,chtyim/cdap,hsaputra/cdap,chtyim/cdap