ES email report formatting

Some requests / suggestions for email reports from es_loganalysis:

Titles / email subject

• Email headers and subject should report the UTC time that was used as the "now" time when querying elasticsearch
• In efficiency summaries: replace "day" with e.g. "T-24 Hrs", "T-7days", "T-30 days" and maybe add a footer to define "T=XXX UTC" (where XXX=the current query time, as in the title/subject)
• Change email subject to e.g. "[IGWN pool report] XXX UTC", where XXX=the current query time, as above.
• in efficiency tables: add a legend in the footer to explain that raw numbers are "counts" and to define efficiency
• Add some intro text like:

IGWN pool payload job counts and success rates for submissions from ldas-osg.ligo.caltech.edu and ldas-osg2.ligo.caltech.edu.
For history time series and more details see: IGWN pool analystics dashboard ([last 24 hours[ / last 7 days] / [last 30 days]).

where the [last 24 hours] etc are links to the grafana dashboard which exactly match the time ranges used for the email report.

• Change job efficiency title to e.g. "Job efficiency for Grid Exerciser tests (ligosearchtag=cit.scheduled.test) and exclude cit.oneshot.test tag.

Tables

• Remove ExitCode column
• Replace successful job count with total job count (I want to see how many jobs in total are landing at each site and we have the efficiency column to see the success rate, so don't limit counts to successful jobs)
• Sort rows in descending order based on total job count in last 30 days
• Include ALL sites in efficiency tables (even if count is zero)
• Replace "nan" with "No jobs in range"
• For each time column (e.g. day, week), add sub-columns for "count" and "efficiency". E.g.:

Last 7 days
Count	Success rate (%)
------	------
0	n/al
52	10 %

(but top cell should span both columns - not supported in markdown)

• Add column borders for readability
• Subsitute GLIDEIN_Site="Unknown" with "Local pool (LIGO-CIT)"

Additional email sections

• Add a "job efficiency summary (all ligosearchtags)" section below the grid-exerciser-only section. Just a duplicate of the existing efficiency table with no filter on the search tag.