* use http endpoints for status updates
* resend updates if www failed to process them
* make leader responsible for synchronizing build updates
* fix tests
* [xdl][exponent] support building ios shell apps with only one sdk version
* [circleci] add jobs for building shell apps for each sdk
* [REVERT ME] [circleci] temporarily disable some jobs
* [circleci] fix shell_app_base_ios_upload_single_sdk
* [xdl][turtle][terraform] support building apps with single sdk in turtle
* [turtle][internal-docs] addresses review comments
* [turtle] add more shell tarballs urls (this has to be changes to the proper values anyway - from ios release branch)
* [circleci] don't pass sdk version to gulp task in shell_app_sim_base_ios job
* [turtle] fix ts errors
* [turtle] remove redundant file with types