Multicolor headers

Summary: This adds a handful of 'Main Header' colors to change the look of Phabricator very slightly. I know I would probably set my dev header to a different color.

Test Plan: Tested each css class and color, can add more in the future.

Reviewers: epriestley, btrahan

Reviewed By: btrahan

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D7731

Author: chadlittle

resources/sprite/main_header/applebloom.png

@@ -0,0 +1,55 @@
+{
+  "version" : 1,
+  "sprites" : {
+    "main-header-applebloom"    : {
+      "name" : "main-header-applebloom",
+      "rule" : ".main-header-applebloom",
+      "hash" : "64822776b129e724709983db1ac5a712"
+    },
+    "main-header-blue"          : {
+      "name" : "main-header-blue",
+      "rule" : ".main-header-blue",
+      "hash" : "b5dd317b7bd35e0592b3f4b66267437c"
+    },
+    "main-header-dark"          : {
+      "name" : "main-header-dark",
+      "rule" : ".main-header-dark",
+      "hash" : "817815d84c0c935b4875f6ecc7dbb526"
+    },
+    "main-header-fluttershy"    : {
+      "name" : "main-header-fluttershy",
+      "rule" : ".main-header-fluttershy",
+      "hash" : "55d4e9f813cf354693290105cf83cf78"
+    },
+    "main-header-green"         : {
+      "name" : "main-header-green",
+      "rule" : ".main-header-green",
+      "hash" : "c230f09e307d167fab3ea0d8c3b33755"
+    },
+    "main-header-nightmaremoon" : {
+      "name" : "main-header-nightmaremoon",
+      "rule" : ".main-header-nightmaremoon",
+      "hash" : "9e7cc7b18d2132d2dd47586ba0cd6400"
+    },
+    "main-header-red"           : {
+      "name" : "main-header-red",
+      "rule" : ".main-header-red",
+      "hash" : "3f12cc098afddb8e6c830ef761dcaa61"
+    },
+    "main-header-scootaloo"     : {
+      "name" : "main-header-scootaloo",
+      "rule" : ".main-header-scootaloo",
+      "hash" : "8cedc359dccab1bbd49cbc69940f566a"
+    },
+    "main-header-yellow"        : {
+      "name" : "main-header-yellow",
+      "rule" : ".main-header-yellow",
+      "hash" : "d920e70a6d2662cfb83e1d7e4b4000fd"
+    }
+  },
+  "scales"  : [
+    1
+  ],
+  "header"  : "\/**\n * @provides sprite-main-header-css\n * @generated\n *\/\n\n.sprite-main-header {\n  background-image: url(\/rsrc\/image\/sprite-main-header.png);\n  background-repeat: repeat-x;\n}\n\n\n",
+  "type"    : "repeat-x"
+}