added save movie option to visualizer rllib

[eugenevinitsky]

Adds flag save_render to visuallizer_rllib which enables you to save the render as a movie in the ~/flow_movies folder.
Changes naming scheme in PygletRenderer to be easier to parse.
Adds drgb option to visuallizer_rllib.

[coveralls]

Pull Request Test Coverage Report for Build 1739

• 12 of 29 (41.38%) changed or added relevant lines in 3 files are covered.
• 8 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+4.9%) to 84.33%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
flow/visualize/visualizer_rllib.py	9	26	34.62%

Files with Coverage Reduction	New Missed Lines	%
tests/fast_tests/test_scenario_base_class.py	2	99.27%
tests/fast_tests/test_environment_base_class.py	2	99.02%
flow/envs/bay_bridge/base.py	4	63.25%

Totals
Change from base Build 1639:	4.9%
Covered Lines:	6684
Relevant Lines:	7926

---

💛 - Coveralls

[AboudyKreidieh]

LGTM. See comment in the redis PR though.