Feature: add androidReaderModeFlags option to pollTag

[robertpoll]

This change adds the androidReaderModeFlags option to poll(). There are a number of flags available but two of the most useful might be:

FLAG_READER_SKIP_NDEF_CHECK
When Android devices detect a tag they will perform an 'NDEF check' which seems to take around 500ms on a typical Samsung phone. Setting this flag has control straight to your app which means you can react much more quickly to tag detection.

FLAG_READER_NO_PLATFORM_SOUNDS
Disable the audio/haptic response on the phone. Useful if your NFC tag gives audio feedback and having the phone also do so is confusing.

The change is backwards compatible as the flag is optional.

[robertpoll]

Thanks for merging – hope people will find it useful.