CB-9782 Implements PlatformApi contract for Android platform.

This closes #226

node_modules/shelljs/src/error.js

@@ -0,0 +1,10 @@
+var common = require('./common');
+
+//@
+//@ ### error()
+//@ Tests if error occurred in the last command. Returns `null` if no error occurred,
+//@ otherwise returns string explaining the error
+function error() {
+  return common.state.error;
+};
+module.exports = error;