[0.40] Commits to cherry-pick

[mkonicek]

Cherry-picking 11 days of commits because 0.40-stable had a huge breaking change for all iOS 3rd party libraries and this is the only way I know how to fix it:
https://github.com/facebook/react-native/commits/0.40-stable

Also cherry-picked:

• Remove dependency on Yeoman (7ea40aa)
• Fix a bug in determining if Yarn is available (9b53408)

Might also need:

• Fix Xcode project: Move headers to project section to fix archive #11395 (cherry picked)

[nihgwu]

@mkonicek I'm afraid that's not enough to resolve the <React/RTCXXX.h> migration issue, #11395 need to be cherry picked too or we can't submit the archived .ipa file

[sjmueller]

Please read my comments regarding changes in 0.40: e1577df#commitcomment-20143360

tl;dr This still completely breaks anyone using Swift. I've tried many different configurations to unbreak our builds, but nothing helps. Please don't release a major version of RN and leave us Swift folks out in the cold!

[ncuillery]

@mkonicek I computed the diff of the template from 0.39.2 to 0.40.0-rc.3:
ncuillery/rn-diff@rn-0.39.2...rn-0.40.0-rc.3
Maybe it could be useful for the team.

I didn't spot anything wrong in the template. But I guess some people would have a sharper eye.

[ide]

Updated 0.40-stable with:

• 46f3ff6 (Move headers to project section to fix archive #11395 - Move headers to project section to fix archive by janicduplessis)
• 8680681 (Updated imports to libyoga*.a in HelloWorld #11606 - Updated imports to libyoga*.a in HelloWorld by ptomasroos)
• bcdf00e ([Podspec] Make Core subspec use a Ruby string array for exclude_files #11664 - [Podspec] Make Core subspec use a Ruby string array for exclude_files by ide)
• 0579efe (Switched to npm hosted boost lib #11469 - Switched to npm hosted boost lib by bestander)
• 5d4b476 (boost is downloaded from https://github.com/react-native-community/boost #11511 - boost is downloaded from https://github.com/react-native-community/boost by bestander)

Sending to CI now.

[nihgwu]

So a new version would be cut tomorrow?

[ide]

After some changes we'll also want to pull in #11667 (CocoaPods fix for tvOS by ptomasroos) and #11676 (Update React to ~15.4.1 instead of using RC by ide).

[ptomasroos]

@ide I've changed my mind on the podspec, its not required to run RN 0.40 only to run master since this commit c92ad5f is not included in the release. We run master and thats why this occurred.