Merge pull request #2147 from ProjectMirador/noCloseWindow

__tests__/src/actions/companionWindow.test.js

__tests__/src/actions/window.test.js

__tests__/src/components/CompanionWindow.test.js

__tests__/src/components/WindowTopBar.test.js

__tests__/src/reducers/companionWindows.test.js

__tests__/src/reducers/windows.test.js

src/components/CompanionWindow.js

src/components/WindowTopBar.js

src/containers/CompanionWindow.js

src/containers/WindowTopBar.js

src/state/actions/companionWindow.js

src/state/actions/window.js

src/state/reducers/companionWindows.js

src/state/reducers/windows.js