Adds $branch param to `push-upstream`
Adds `with-fresh-test-db` command
Adds JSON-related curl functions
with-fresh-test-db: fixes return value
with-fresh-test-db: prevents permanent keepdb
Adds cuke = cucumber with timestamped log
Fixes conditional for with-fresh-test-db
Defaults command to $SHELL in with-fresh-test-db
Adds $testdb or $DATABASE_URL to prompt
Adds `in-btrfs-snapshot` function
Makes wrapper functions "invisible" to completion

`with-fresh-test-db` and `in-btrfs-snapshot` both act like precommand
modifiers, in a manner similar to `xargs` or `env`.
Silences migrations under `with-fresh-test-db`
Adds $cuke_logs and $cuke_prefix config vars

cuke_logs controls where the log will end up (default ./log/)

cuke_prefix adds an optional prefix (followed by a dot) to the log name