Fix display far in /year; decide on year definition

This MR fixes a unit conversion bug that incorrectly displayed an event's FAR in per-year units. The database value of far is always in Hz (fingers crossed), but it converted on-the-fly to per-year so it's more easily read by humans on the webpage.

This brings up a larger question, which I will leave to the masses to answer: how many days are in a year?

In today's gstlal review call @wanting.niu @jolien-creighton cited some hard-coded values in gstlal (?) and in GraceDB that fixed the numbers of days per year as the Julian value (365.25 days).

@brandon.piotrzkowski correctly pointed out that GWCelery is using the civil definition (365.0 days) for defining public alert thresholds.

Ultimately this discrepancy is only going to result in a small decimal place difference on a webpage, but we should at least be consistent. Interested parties, could you please vote below?

Question: Should GraceDB calculate the display year^-1 FAR value using the Julian or civil calendar year? Tagging some pipeline and EMFollow parties. Please place your response in a comment or edit the table with a with your preference. Note that this was coded to be a settings switch in GraceDB so it can in theory be changed, but it's defaulting to the Julian definition at the moment.

	Julian, 365.25	Civil, 365
@jolien-creighton
@chad-hanna
@tito-canton
@benoit.mours
@brandon.piotrzkowski
@cody.messick