RV Plotting adds Gamma twice?

[semaphoreP]

Describe the bug
I think the gamma offset is corrected for twice in the plot_orbits function.

To Reproduce
Run RV Tutorial notebook (the one for HD 4747) and the plot_orbits output is offset from the data. See last figure of tutorial: https://orbitize.readthedocs.io/en/latest/tutorials/RV_MCMC_Tutorial.html

Expected behavior
The RV points should line up with the model

Screenshots
These look like duplicate lines

orbitize/orbitize/plot.py

Lines 554 to 555 in 76ced1f

	rvs-=med_ga[i]
	rvs -= best_post[results.param_idx[gams[i]]]

Desktop (please complete the following information):

• OS: ubuntu
• orbitize! Version [2.0.0]

Additional context

[sblunt]

Addressed in PR #318. Duplicate of Issue #309.