Revert "Revert "Merge pull request #664 from code-dot-org/script-stages-empty""

This reverts commit 5b36a1865485b331079cafbb1c749bb3d52342b1.
Handle multiple script import positionings correctly
Attempt to repro stage gap creation
Add note on test
step mode tests
Merge pull request #701 from code-dot-org/stepMode

step mode tests
Automatically built.
dont use localhost
Merge pull request #703 from code-dot-org/stepMode

dont use localhost
Support empty stages and stage reordering
Add simple jigsaw visit test
Merge pull request #694 from code-dot-org/consistent_stage_numbering

Un-revert Toby's position import change, make stage importing idempotent with respect to script_level positions
Remove timing-dependent run button test
Merge pull request #706 from code-dot-org/remove_run_button_test

Remove timing-dependent run button test
Merge branch 'finished' of github.com:code-dot-org/dashboard into finished
Merge branch 'finished' into lowerfooter