`read_observations()` assignment

[btupper]

@solanoalex OK!

@tyshawnrene Have you pushed your updates? I see the orginal read_observations() in functions/observations.R but not one modified for your own use. Or should I look somewhere else for it?

@vameringer OK!

@taragorman OK!

@DanielSweeney25 OK! I keep forgetting that you made a read_obs() as a substitute for read_observations() - which is fine unless it annoys you down the road.

@zane-chutkow OK! Lots of customized filtering appeals to one's inner sloth (no offense to sloths who are supremely efficient)

@tenzytaec26 OK! Interesting surgical use of filtering. I suppose you might consider using dplyr's drop_na() when you want to drop any row where NA appears in any variable.

@J-Kapl OK! Check out dplyr's between() when filtering between ranges (like dates). It works similar to how you have used compound tests in one filter()

@ArianaRaschidFarrokhi OK!