Move markdown-it-imsize dev-dependency to production

package.json

@@ -63,6 +63,7 @@
     "markdown-it-checkbox": "^1.1.0",
     "markdown-it-emoji": "^1.1.1",
     "markdown-it-footnote": "^3.0.0",
+    "markdown-it-imsize": "^2.0.1",
     "md5": "^2.0.0",
     "mixpanel": "^0.4.1",
     "moment": "^2.10.3",
@@ -102,7 +103,6 @@
     "grunt-electron-installer": "^1.2.0",
     "history": "^1.17.0",
     "jsdom": "^9.4.2",
-    "markdown-it-imsize": "^2.0.1",
     "merge-stream": "^1.0.0",
     "nib": "^1.1.0",
     "react-color": "^2.2.2",

yarn.lock

@@ -1,7 +1,5 @@
 # THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
 # yarn lockfile v1
-
-
 "@rokt33r/markdown-it-math@^4.0.1":
   version "4.0.2"
   resolved "https://registry.yarnpkg.com/@rokt33r/markdown-it-math/-/markdown-it-math-4.0.2.tgz#87c7172f459833b05e406cfc846e0c0b7ebc24ef"
@@ -4115,7 +4113,7 @@ markdown-it-footnote@^3.0.0:
   version "3.0.1"
   resolved "https://registry.yarnpkg.com/markdown-it-footnote/-/markdown-it-footnote-3.0.1.tgz#7f3730747cacc86e2fe0bf8a17a710f34791517a"
 
-markdown-it-imsize@^2.0.1:
+markdown-it-imsize:
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/markdown-it-imsize/-/markdown-it-imsize-2.0.1.tgz#cca0427905d05338a247cb9ca9d968c5cddd5170"
 
@@ -7042,3 +7040,4 @@ zip-stream@^1.1.0:
     compress-commons "^1.1.0"
     lodash "^4.8.0"
     readable-stream "^2.0.0"
+