Revert "Switch assets bucket to the new batch_view_scratch bucket"

This reverts commit a66ffebb6076f9bb088cf9919c1b6bfc186bc8c9.
add graphs to .gitignore
isolate Template specs from changes to S3PathBuilder
use Pathology to make S3PathBuilder config more flexible
add start_time to default config for staging, to allow schedule overrides
dynamically build S3PathBuilder#to_hash, to support templates added via config
Merge pull request #52 from swipely/configure_s3_paths

Configure s3 paths