Pip 1220 clip chrom end for peaks

[leepc12]

See details here. https://encodedcc.atlassian.net/browse/PIP-1220

Clip peak files' genome coordinate (start/end) with USCS tool bedClip. What is clipped:

• Raw peak from SPP (TF) / MACS2 (Histone)
• IDR peak (12-col BED narrowPeak)
  • We don't need to clip overlap peak since it's simply based on bedtools intersect).
• IDR unthresholded peak (20-col BED)