Scholarship years update

Resolves #522

Winner's Gallery year period in title is now set dynamically. If no prior year scholarship exists, but winner's gallery exists, then the year is set to prior year timeline based on current timeline, so there's a proper fallback.

Updated collection query for current scholarship so it grabs the latest if more than one scholarship exists in database. This is based on the scholarship start date.

Also did some code cleanup and made some efficiency gains with both reducing the number of SQL queries and caching some queries. On home page, SQL queries went down from **8** queries to **3** :dancer: 

@angaither 

CC: @barryclark @DFurnes 
So I tried that, and it actually does another SQL query; same thing in the prior code w/ the `pluck()`. I confirmed it when outputting the sql queries to visualize what was going on. So it's either NOT use the static method and request things specifically but since we use that static method elsewhere (and now I'm caching it), it's actually better this way.