Create tag/plot for analog board saturations

Checks set of analog board monitors for voltages exceeding +/-9.5 V around the time of lockloss, and creates a tag/plot if it does. Similar to the BRS plot, this one (by commissioner suggestion) does not show up on the website if there is no tag. Channels names have been verified at LLO, they should also have a 10V limit on their boards.

BOARD_SAT tag: Screen_Shot_2019-08-30_at_4.46.38_PM

Collapsed board saturation section: Screen_Shot_2019-08-30_at_4.47.16_PM

Open board saturation section: Screen_Shot_2019-08-30_at_4.47.28_PM

Board saturation png: https://ldas-jobs.ligo-wa.caltech.edu/~yannick.lecoeuche/events/1232/246977/board_sat.png

Closes #59 (closed)