Adds property declarations to generated Objective-C for annotated fields. See Apple's @property documentation.

Notes:

• Invalid attributes are reported as errors.
• readwrite, strong (when using ARC), and atomic attributes are removed since they are defaults.
• Strings will include the copy attribute.

Example:

class Foo {
  @Property("copy, nonatomic") protected String bar;
}

generates:

@property (copy, nonatomic) NSString *bar;