Merge pull request #1080 from code-dot-org/finished

finished -> levelbuilder
A lot of work toward enabling Stanford and hint visibility experiments:
- Specified levels on which experiments should take place.
- Switched to using ip addresses, rather than user ids, to determine
  experiment options.
A lot of work toward enabling Stanford and hint visibility experiments:
- Specified levels on which experiments should take place.
- Switched to using ip addresses, rather than user ids, to determine
  experiment options.
Added ip_hash field to activity_hints.
Improved tests.
Merge branch 'experiment' of github.com:code-dot-org/dashboard into experiment

Conflicts:
	app/controllers/application_controller.rb
Removed tests duplicated in prior merge.
Minor improvements.
ignore config/scripts/.hints_imported
script changes
Merge pull request #1095 from code-dot-org/level-builder

Level builder -> Finished
Dropbox changes
Merge pull request #1096 from code-dot-org/finished

finished -> delivered
UI improvements to new signin section page.
[Finishes #75752104] Convert strings to ints in maze levels
Merge pull request #1098 from code-dot-org/stringToNumber

[Finishes #75752104] Convert strings to ints in maze levels
Merge pull request #1099 from code-dot-org/finished

finished -> levelbuilder
More polish.
Merge pull request #1100 from code-dot-org/finished

DTD
Merge pull request #1097 from code-dot-org/signinsectionui

UI improvements to new signin section page.