Implementation of testing GR parameterized test

This is an implementation of the parameterized test for testing General Relativity. A set of PE runs on GW170814 are done and the results on each of the testing parameters can be found at [1], which is consistent with the result reported at Table 5, Fig 8 and Fig 9 in [2].

[1] https://ldas-jobs.ligo.caltech.edu/~tsun-ho.pang/bilbyTGR/pe_summary/ [2] https://arxiv.org/abs/1903.04467