fix #191 use LOG instead of cout

fix #189 update log module

fix #183 git log printer

fix #187 add mul_op and mul_op_test

update build script and CMakList

fix #181 Run() in elementwise_add_op.h

fix #176 add elementwise_add_op

fix #178 modify dirty code

fix #172，fix #173 simplify operator interfaces & dynamic release variable

fix #171 update clang-format & update code stylee.