Feature: Get app version from Google Play Store rather than hosting a json

[robertofrontado]

I really like this library 👍 Very nice work!

But I realized that it didn't work the same way as the iOS version

So I added this is the new method:

public void checkVersion(Activity activity, SirenVersionCheckType versionCheckType) {
...
}

So there is no need to pass the url of the json 🙌

Note: I added this as an extra functionality, so if you still want to keep the updates alerts via json you can 👍

[robertofrontado]

@eggheadgames I think you will need to handle that error in CircleCI

* What went wrong:
A problem occurred configuring project ':library'.
> Failed to install the following Android SDK packages as some licences have not been accepted.
     build-tools;27.0.3 Android SDK Build-Tools 27.0.3

[mikemee]

Thanks @robertofrontado ! I'm swamped at the moment, but I've made a note to look at this deeper in a week or so (when some iOS 12 urgent stuff has hopefully passed!).

I did look at doing it this way originally, but my research suggested it was pretty dicey to do it that way, between various versions of the Play store, etc. etc. However, I'll take a look at the PR, and providing it as an option might make sense for those who want to try it.

Thanks for the other cleanup too!

[robertofrontado]

@mikemee Thank you!

Indeed, I thought this as a complement of the current functionality, which is already working nicely 👍 so there was no need to change that.

If you have any comments please let me know 👋

Hope it can get merged soon!

[StainlessStlRat]

Any reason this was never pushed? I'd like to use the library, but don't want to add another step I have to remember every time an update releases.

[robertofrontado]

@StainlessStlRat No idea, but you can use my fork for now until this gets merged

implementation 'com.github.robertofrontado:Siren:1.7.0' // This is a fork of https://github.com/eggheadgames/Siren, because that one didn't fetch the version number from google play yet