Summary: add "main" field instead of "name" to bower.json

Test plan:
 - Run `bower install katex` from /tmp
 - Verify that there are no errors when running the command
 - Verify that `bower_components/katex/dist/` contains all the build files
 - Verify that the version is 0.4.2

Auditors: emily

package.json

@@ -1,6 +1,6 @@
 {
   "name": "katex",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "description": "Fast math typesetting for the web.",
   "main": "katex.js",
   "repository": {