Update to the latest Electron version (1.8.7)

It inculdes security fixes, bug fixes and improvementts. See:
https://electronjs.org/releases

Reason for upgrading from 1.7.X to 1.8.X:

"We can not reasonably back port every bug fix and every feature to
older versions of Electron. 1.8.x is now a stable release line and if
you require this fix you should update to that stream."

https://github.com/electron/electron/issues/9860#issuecomment-365517773

yarn.lock

@@ -1,7 +1,6 @@
 # THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
 # yarn lockfile v1
 
-
 "@ava/babel-plugin-throws-helper@^2.0.0":
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/@ava/babel-plugin-throws-helper/-/babel-plugin-throws-helper-2.0.0.tgz#2fc1fe3c211a71071a4eca7b8f7af5842cd1ae7c"
@@ -79,9 +78,9 @@
     fs-plus "2.x"
     optimist "~0.4.0"
 
-"@types/node@^7.0.18":
-  version "7.0.65"
-  resolved "https://registry.yarnpkg.com/@types/node/-/node-7.0.65.tgz#c160979ff66c4842adc76cc181a11b5e8722d13d"
+"@types/node@^8.0.24":
+  version "8.10.17"
+  resolved "https://registry.yarnpkg.com/@types/node/-/node-8.10.17.tgz#d48cf10f0dc6dcf59f827f5a3fc7a4a6004318d3"
 
 abab@^1.0.3, abab@^1.0.4:
   version "1.0.4"
@@ -2577,11 +2576,11 @@ electron-winstaller@^2.2.0:
     lodash.template "^4.2.2"
     temp "^0.8.3"
 
-electron@1.7.11:
-  version "1.7.11"
-  resolved "https://registry.yarnpkg.com/electron/-/electron-1.7.11.tgz#993b6aa79e0e79a7cfcc369f4c813fbd9a0b08d9"
+electron@1.8.7:
+  version "1.8.7"
+  resolved "https://registry.yarnpkg.com/electron/-/electron-1.8.7.tgz#373c1dc4589d7ab4acd49aff8db4a1c0a6c3bcc1"
   dependencies:
-    "@types/node" "^7.0.18"
+    "@types/node" "^8.0.24"
     electron-download "^3.0.1"
     extract-zip "^1.0.3"