[fix] support for Animated transform styles

Animated uses 'setNativeProps' to update styles. This mutates the DOM
without using React. But the code path was not adding 'px' units to
transform values and browsers were ignoring the style.

Fix #129

src/apis/StyleSheet/__tests__/processTransform-test.js

@@ -14,7 +14,7 @@ suite('apis/StyleSheet/processTransform', () => {
 
     assert.deepEqual(
       processTransform(style),
-      { transform: 'scaleX(20) rotate(20deg)' }
+      { transform: 'scaleX(20px) rotate(20deg)' }
     )
   })
 

src/apis/StyleSheet/processTransform.js

@@ -1,7 +1,10 @@
+import normalizeValue from './normalizeValue'
+
 // { scale: 2 } => 'scale(2)'
 const mapTransform = (transform) => {
-  var key = Object.keys(transform)[0]
-  return `${key}(${transform[key]})`
+  const type = Object.keys(transform)[0]
+  const value = normalizeValue('transform', transform[type])
+  return `${type}(${value})`
 }
 
 // [1,2,3,4,5,6] => 'matrix3d(1,2,3,4,5,6)'