[babel] configure a specific cache path

Babel needs a path to write its cache, which it automatically places to $HOME or tmp if
$HOME is not defined. This causes problems when the $HOME directory is not writable or
we just do not want to write to such a central location. So This moves the cache to the
project directory by setting the BABEL_CACHE_PATH environment variable.

.gitignore

@@ -19,3 +19,4 @@ webpackstats.json
 config/kibana.dev.yml
 coverage
 selenium
+.babelcache.json

src/cli/index.js

@@ -1,2 +1,5 @@
-require('babel/register')(require('../optimize/babelOptions').node);
+// load the babel options seperately so that they can modify the process.env
+// before calling babel/register
+const babelOptions = require('../optimize/babelOptions').node;
+require('babel/register')(babelOptions);
 require('./cli');

src/optimize/babelOptions.build.js

@@ -1,4 +1,5 @@
-var fromRoot = require('requirefrom')('src/utils')('fromRoot');
+var fromRoot = require('path').resolve.bind(null, __dirname, '../../');
+process.env.BABEL_CACHE_PATH = fromRoot('optimize/.babelcache.json');
 
 exports.webpack = {
   stage: 1,

src/optimize/babelOptions.js

@@ -1,3 +1,5 @@
+process.env.BABEL_CACHE_PATH = require('path').resolve(__dirname, '../../optimize/.babelcache.json');
+
 exports.webpack = {
   stage: 1,
   nonStandard: false,