add connect-redis for redis support (#183)

Redis is an optional dependency of Grist. When available, it can
be used for session storage, for supporting a pool of workers, and
for managing webhook delivery. This commit adds connect-redis to
package.json to simplify enabling Redis for the end user.

package.json

@@ -95,6 +95,7 @@
     "brace": "0.11.1",
     "collect-js-deps": "^0.1.1",
     "components-jqueryui": "1.12.1",
+    "connect-redis": "3.4.0",
     "cookie-parser": "1.4.3",
     "csv": "4.0.0",
     "diff-match-patch": "1.0.5",

yarn.lock

@@ -1917,6 +1917,14 @@ configstore@^5.0.1:
     write-file-atomic "^3.0.0"
     xdg-basedir "^4.0.0"
 
+[email protected]:
+  version "3.4.0"
+  resolved "https://registry.yarnpkg.com/connect-redis/-/connect-redis-3.4.0.tgz#4040dd3755bddbf93478fb84937a74052c31b965"
+  integrity sha512-YKPSO9tLwzUr8jzhsGMdSJUxevWrDt0ggXRcTMb+mtnJ/vWGlWV7RC4VUMgqvZv3uTGDFye8Bf7d6No0oSVkOQ==
+  dependencies:
+    debug "^4.0.1"
+    redis "^2.8.0"
+
 console-browserify@^1.1.0:
   version "1.2.0"
   resolved "https://registry.yarnpkg.com/console-browserify/-/console-browserify-1.2.0.tgz#67063cef57ceb6cf4993a2ab3a55840ae8c49336"
@@ -2175,6 +2183,13 @@ debug@^3.0.0:
   dependencies:
     ms "^2.1.1"
 
+debug@^4.0.1:
+  version "4.3.4"
+  resolved "https://registry.yarnpkg.com/debug/-/debug-4.3.4.tgz#1319f6579357f2338d3337d2cdd4914bb5dcc865"
+  integrity sha512-PRWFHuSU3eDtQJPvnNY7Jcket1j0t5OuOsFzPPzsekD52Zl8qUfFIPEiswXqIvHWGVHOgX+7G/vCNNhehwxfkQ==
+  dependencies:
+    ms "2.1.2"
+
 decamelize@^1.1.2, decamelize@^1.2.0:
   version "1.2.0"
   resolved "https://registry.yarnpkg.com/decamelize/-/decamelize-1.2.0.tgz#f6534d15148269b20352e7bee26f501f9a191290"
@@ -6009,7 +6024,7 @@ redis-parser@^2.6.0:
   resolved "https://registry.yarnpkg.com/redis-parser/-/redis-parser-2.6.0.tgz#52ed09dacac108f1a631c07e9b69941e7a19504b"
   integrity sha1-Uu0J2srBCPGmMcB+m2mUHnoZUEs=
 
-[email protected]:
+[email protected], redis@^2.8.0:
   version "2.8.0"
   resolved "https://registry.yarnpkg.com/redis/-/redis-2.8.0.tgz#202288e3f58c49f6079d97af7a10e1303ae14b02"
   integrity sha512-M1OkonEQwtRmZv4tEWF2VgpG0JWJ8Fv1PhlgT5+B+uNq2cA3Rt1Yt/ryoR+vQNOQcIEgdCdfH0jr3bDpihAw1A==