Merge pull request #1855 from ProjectMirador/1780-canvas-level-md

__tests__/integration/mirador/window_sidebar.test.js

__tests__/src/components/LabelValueMetadata.test.js

__tests__/src/components/WindowSideBarInfoPanel.test.js

__tests__/src/components/WindowSideBarPanel.test.js

__tests__/src/selectors/index.test.js

src/components/LabelValueMetadata.js

src/components/Window.js

src/components/WindowMiddleContent.js

src/components/WindowSideBar.js

src/components/WindowSideBarInfoPanel.js

src/components/WindowSideBarPanel.js

src/containers/WindowSideBar.js

src/containers/WindowSideBarButtons.js

src/containers/WindowSideBarInfoPanel.js

src/containers/WindowSideBarPanel.js

src/state/selectors/index.js