update to map gl-0.27

[toabey]

"visgl#112"
UPD: I got this fixed. It turned out I did not have Flow transpiler in my babel config.
npm install babel-plugin-transform-flow-strip-types --save-dev
In .babelrc or "babel" section in package.json:
"plugins": [
"...other plugins...",
"transform-flow-strip-types"
],
If your webpack loader is configured to ignore stuff in node_modules (which is a good idea for build performance), amend this rule to make mapbox-gl/js an exception:
loaders: [{
test: /.js$/,
loader: 'babel',
// exclude: /node_modules/, // remove
exclude: /node_modules/(?!mapbox-gl/js)/, // add
}, {
// ...
If you've already had .flowconfig in your project's directory, make sure that node_modules is not excluded there.