WASHINGTON — Senate conservatives and liberals on Thursday united behind an overhaul of the criminal justice system, a rare bipartisan agreement that would allow some non-violent drug offenders to get reduced prison sentences and give judges greater discretion in sentencing.The legislation, years in the making, comes as disparate voices have spoken as one in saying the current system is broken, from President Barack Obama to the American Civil Liberties Union to the conservative Koch Industries.At the same time …