Dashboard improvements

[bourque]

Some potential improvements:

• The plots on the dashboard may be too big for a typical browser window on a mac laptop. The plots should be made smaller, or ideally scale automatically with the size of the browser
• There is a question mark in the y-axis label of the storage vs. time plot

Credit to Jo Taylor for the suggestions!

[cracraft]

Check over all of the plots to see how reasonable the numbers of files are. The File counts per filter and number of files per instrument plots also seem off... way too large in the first case, and too small in the second.

[stscijgbot-jwql]

This issue is tracked on JIRA as JWQL-233.