Remove support for password property and only use secureTextEntry

Summary:
Reduce the public surface area of TextInput.  It only exposes a secureTextEntry property, but on Android was also accepting password as a prop.
This removes that.

Reviewed By: javache

Differential Revision: D3392223

fbshipit-source-id: 67c36fbe16fe493e2841d5d9deb78e3be2209ebd

ReactAndroid/src/androidTest/js/TextInputTestModule.js

@@ -90,7 +90,7 @@ var TextInputTestApp = React.createClass({
           autoFocus={true}
           keyboardType='numeric'
           multiline={true}
-          password={true}
+          secureTextEntry={true}
           defaultValue="This is text"
           testID="textInput1"
         />
@@ -101,7 +101,7 @@ var TextInputTestApp = React.createClass({
           autoFocus={false}
           keyboardType='default'
           multiline={false}
-          password={false}
+          secureTextEntry={false}
           placeholder='1234'
           testID="textInput2"
         />