add script_id to user_levels and activities
* migration to add script id to user_levels and activities
* script to copy existing user_levels to new ones for each relevant
  script
* I don't think it's necessary to do the same for activities because we
  don't actually query activities in a script context for any user
  facing features (we use user_level where we need to do something like
  this)
never mind that, never touch the activities table
code to write user_levels with script_ids
Course 4 block at studio.code.org.
[Finishes #83811162] Allow disabling sharing pop-up in freeplay Play Lab levels
Make FreePlay + no-sharing feedback messaging consistent with other levels.
Disable 'show code' button in feedback dialog when Play Lab workspace is hidden.
Merge pull request #638 from code-dot-org/staging

DTT
Merge pull request #640 from code-dot-org/test

DTP
Moving changes to new instance
Merge pull request #644 from code-dot-org/staging

Deploy levelbuilder
Merge pull request #650 from code-dot-org/staging

Deploy levelbuilder
Merge staging
=== instead of ==
cleanup
Use the new build env on Travis

more ram, more cpu, better boot times, caching built in
Add course 4 video keys
more playlab fiddling
Basic print function (no context sensitivity)
Updated docs for levelbuilder
Merge pull request #652 from code-dot-org/i18n

localize instructions frozen, scrat, standalone artist