Use proptypes-parser for cleaner PropTypes.

I've created [proptypes-parser](https://github.com/joonhocho/proptypes-parser) to make it easier to write PropTypes for React components.

Instead of writing

``` javascript
const propTypes = {
number: PropTypes.number,
string: PropTypes.string.isRequired,
boolean: PropTypes.bool,
function: PropTypes.func.isRequired,
date: PropTypes.instanceOf(Date).isRequired,
object: PropTypes.object.isRequired,
shape: PropTypes.shape({
nested: PropTypes.number,
array: PropTypes.arrayOf(PropTypes.number),
must: PropTypes.bool.isRequired,
}).isRequired,
array: PropTypes.arrayOf(
PropTypes.Number.isRequired,
).isRequired,
arrayOfObjects: PropTypes.arrayOf(
PropTypes.shape({
value: PropTypes.string,
}).isRequired
),
node: PropTypes.node
element: PropTypes.element.isRequired,
message: PropTypes.instanceOf(Message).isRequired,
any: PropTypes.any.isRequired,
};
```

Write

``` javascript
const propTypes = parsePropTypes(`{
number: Number
string: String!
boolean: Boolean
function: Function!
date: Date!
object: Object!
shape: {
nested: Number
array: [Number]
must: Boolean!
}!
array: [Number!]!
arrayOfObjects: [{
value: String
}!]
node: Node
element: Element!
message: Message!
any: Any!
}`);
```

It's cleaner, easier, and less error-prone way to write PropTypes.
It's also fast!

I will be happy to make PR if you'd like to use it.