Establish a convention for forcing jsx rebuilds.

Pull request #526 updated the behavior of vendor/constants.js without
changing any source files or the bin/jsx-internal script, so files that
should have been rebuilt (like utils/__tests__/ImmutableObject-test.js)
were not automatically rebuilt (unless you knew to do `grunt clean` or
`rm -rf .module-cache` manually).

This commit allows us to bump a version number when we know the transform
toolchain has been altered in a way that will not be visible to
commoner/jsx.

With this convention, if we reset to an older revision (e.g. during a git
bisect) and the appropriate cached module files are still in the
.module-cache/, they can be used without rebuilding. That's why I prefer
this approach to just deleting the .module-cache/.

Closes #104.
Closes #496.
Closes #530.

grunt/config/jsx/jsx.js

@@ -10,6 +10,7 @@ var rootIDs = [
 var getDebugConfig = function() {
   return {
     "debug": true,
+    "jsxConfig": grunt.config.data.pkg.jsxConfig,
     "constants": {
       "__VERSION__": grunt.config.data.pkg.version,
       "__DEV__": true
@@ -33,6 +34,7 @@ var test = {
     return {
       "debug": true,
       "mocking": true,
+      "jsxConfig": grunt.config.data.pkg.jsxConfig,
       "constants": {
         "__VERSION__": grunt.config.data.pkg.version,
         "__DEV__": true
@@ -49,6 +51,7 @@ var release = {
   getConfig: function() {
     return {
       "debug": false,
+      "jsxConfig": grunt.config.data.pkg.jsxConfig,
       "constants": {
         "__VERSION__": grunt.config.data.pkg.version,
         "__DEV__": false

package.json

@@ -64,5 +64,8 @@
   "engines": {
     "node": ">=0.10.0"
   },
-  "preferGlobal": true
+  "preferGlobal": true,
+  "jsxConfig": {
+    "version": 1
+  }
 }