Storybook: add decorator for Redux, React Router, and Material-UI. Also init translatations.

.storybook/preview-head.html

+<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Roboto:300,400,500">
\ No newline at end of file

.storybook/preview.js

+import { addDecorator } from '@storybook/react'
+import { DocsPage, DocsContainer } from '@storybook/addon-docs/blocks'
+import React from 'react'
+import { createStore } from 'redux'
+import { Provider } from 'react-redux'
+import { Router } from 'react-router-dom'
+import { createBrowserHistory } from 'history'
+import intl from 'react-intl-universal'
+import { MuiThemeProvider, createMuiTheme } from '@material-ui/core/styles'
+import deepPurple from '@material-ui/core/colors/deepPurple'
+import localeEN from '../src/client/translations/sampo/localeEN'
+import localeFI from '../src/client/translations/sampo/localeFI'
+import localeSV from '../src/client/translations/sampo/localeSV'
+import reducer from '../src/client/reducers'
+
+import '../src/client/index.css'
+
+const store = createStore(reducer)
+
+intl.init({
+  currentLocale: 'en',
+  locales: {
+    en: localeEN,
+    fi: localeFI,
+    sv: localeSV
+  }
+})
+
+const theme = createMuiTheme({
+  palette: {
+    primary: deepPurple
+  },
+  overrides: {
+    MuiTooltip: {
+      tooltip: {
+        fontSize: '1 rem'
+      }
+    },
+    MuiExpansionPanel: {
+      root: {
+        '&$expanded': {
+          marginTop: 8,
+          marginBottom: 8
+        }
+      }
+    },
+    MuiButton: {
+      endIcon: {
+        marginLeft: 0
+      }
+    }
+  }
+})
+
+addDecorator(Story => (
+  <Provider store={store}>
+    <Router history={createBrowserHistory()}>
+      <MuiThemeProvider theme={theme}>
+        <Story />
+      </MuiThemeProvider>
+    </Router>
+  </Provider>
+))