[zanata/zanata-platform] 8953b2: Avoid pre-release yarn 1.4

[GitHub]

  Branch: refs/heads/typescript
  Home:   https://github.com/zanata/zanata-platform
  Commit: 8953b245bc81d911dd14bf1fb956d3bf11e43fe4
      https://github.com/zanata/zanata-platform/commit/8953b245bc81d911dd14bf1fb956d3bf11e43fe4
  Author: Sean Flanigan <sflaniga at redhat.com>
  Date:   2018-02-01 (Thu, 01 Feb 2018)

  Changed paths:
    M server/zanata-frontend/pom.xml

  Log Message:
  -----------
  Avoid pre-release yarn 1.4