upgrade pandas to 0.15.0
upgrade pandas to 0.15.0

https://github.com/pydata/pandas/releases/tag/v0.15.0
chrisdamba/mining,mlgruby/mining,seagoat/mining,avelino/mining,AndrzejR/mining,mining/mining,seagoat/mining,mlgruby/mining,AndrzejR/mining,chrisdamba/mining,mining/mining,jgabriellima/mining,mlgruby/mining,avelino/mining,jgabriellima/mining