Fix yarn.lock electron entry

1.8.0 doesn't exist anymore it looks like.

Supercedes & fixes #898

yarn.lock

@@ -754,8 +754,8 @@ electron-download@^3.0.1:
     sumchecker "^1.2.0"
 
 electron@^1.4.4:
-  version "1.8.0"
-  resolved "https://registry.yarnpkg.com/electron/-/electron-1.8.0.tgz#896f429b1e664f496f62b9cc7ee6a67a71375f31"
+  version "1.8.1"
+  resolved "https://registry.yarnpkg.com/electron/-/electron-1.8.1.tgz#19b6f39f2013e204a91a60bc3086dc7a4a07ed88"
   dependencies:
     "@types/node" "^8.0.24"
     electron-download "^3.0.1"
@@ -2309,9 +2309,9 @@ preserve@^0.2.0:
   version "0.2.0"
   resolved "https://registry.yarnpkg.com/preserve/-/preserve-0.2.0.tgz#815ed1f6ebc65926f865b310c0713bcb3315ce4b"
 
-prettier@^1.4.1:
-  version "1.7.0"
-  resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.7.0.tgz#47481588f41f7c90f63938feb202ac82554e7150"
+prettier@^1.7.0:
+  version "1.7.4"
+  resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.7.4.tgz#5e8624ae9363c80f95ec644584ecdf55d74f93fa"
 
 pretty-bytes@^1.0.2:
   version "1.0.4"