Add fulltext search filter

[bensheldon]

Closes #432.

Bit of a spike, but wanted to open up for feedback.

Some quirks:

• When searching jobs, it only searches the properties of the most recent execution. So while the "Last Error" (i.e. the error from the previous execution) of a job will appear in the dashboard, it's not queryable.
• There is no search indexing, so this results in a row scan.