Bqup

- Add -r and -e to readme
- Add support for routines with no args

* Bump target Python from 3.6 to 3.7
* Fix verbose flag
* Fix inconsistent key order in exported json schemata

- Made export of routines optional
- Added support for retrying when retrieving tables
- Now exports empty `*.table.json` files even without `-x` flag
- Added support for filtering of datasets by regex

Added support for exporting routines

Added documentation, cleanup, and checks

Minor cleanup