Endorse AdoptOpenJDK instead of Oracle OpenJDK
Endorse AdoptOpenJDK instead of Oracle OpenJDK

This commit changes the message that appears when Homebrew detects
that a Java requirement is unmet.

The new message will say:

```
Install AdoptOpenJDK with Homebrew Cask:
  brew cask install adoptopenjdk
```

And for Java 8:

```
Install AdoptOpenJDK 8 with Homebrew Cask:
  brew cask install homebrew/cask-versions/adoptopenjdk8
```

sjackman/homebrew,vitorgalvao/brew,sjackman/homebrew,nandub/brew,claui/brew,nandub/brew,EricFromCanada/brew,konqui/brew,reitermarkus/brew,JCount/brew,EricFromCanada/brew,MikeMcQuaid/brew,EricFromCanada/brew,claui/brew,EricFromCanada/brew,konqui/brew,JCount/brew,reitermarkus/brew,MikeMcQuaid/brew,nandub/brew,claui/brew,claui/brew,mahori/brew,nandub/brew,konqui/brew,Homebrew/brew,mahori/brew,Homebrew/brew,reitermarkus/brew,Homebrew/brew,MikeMcQuaid/brew,mahori/brew,konqui/brew,mahori/brew,vitorgalvao/brew,vitorgalvao/brew,sjackman/homebrew,JCount/brew,sjackman/homebrew,MikeMcQuaid/brew,JCount/brew,reitermarkus/brew,Homebrew/brew,vitorgalvao/brew