Created by: JepsonWong

add CI check for sequence ops' unittests.

It is required that the LoDTensor in sequence related OP unittests must be obtained by self.get_sequence_instance_size_0_input() function to cover the case of instance size = 0.

• test case1: white list does not have sequence_reshape op, and its unittest does not have required function call. http://ci.paddlepaddle.org/viewLog.html?buildId=270297&buildTypeId=YYTest_PrCiCpuPy2&tab=buildLog&branch_YYTest=pull%2F19787

• test case2: white list updated. http://ci.paddlepaddle.org/viewLog.html?buildId=270357&tab=buildLog&buildTypeId=YYTest_PrCiCpuPy2&logTab=tree&filter=all