Add header to meth offender table

- Write header before county loop
- Refactor dom extraction into separate function
- Fix csv path
Merge pull request #3 from sburns/fix-meth-header

Add header to meth offender table
Fix single-offender counties in meth table
Merge pull request #4 from sburns/fix-empty-meth-county

Fix single-offender counties in meth table