Merge WPAndroid and WCAndroid changes (Take 2)

[oguzkocer]

This is my second attempt at merging changes to the library from WPAndroid and WCAndroid. Here is the first one: #56. I've had to manually track down every single line of change to compose this PR, so to say it's error prone would be an understatement. I think the best way to review these changes is to review the client PRs. The reason is, this PR merges changes from WPAndroid and WCAndroid, however clients PRs (in theory) should only change each other's changes, so it's easier to refer where that change has been made.

1. 5315e37 copies WCAndroid's login library and only accepts changes made in WCAndroid. WPAndroid devs have been keeping this library mostly up to date, so copying WCAndroid would show up a lot of removed code that WPAndroid devs have added.
2. 5f159e7 copies WPAndroid's login library and only accepts changes made in WPAndroid. Since WPAndroid devs were mostly keeping the library up to date (and they actually pinged me while trying to update the library again) this contains changes made recently.
3. ebfd876 updates default FluxC version to the latest version which fixes the lazysodium dependency issue (Bintray shutting down and lazysodium moving to mavenCentral)
4. 5e642dd fixes the lint issue for android:tint
5. 79b786c updates gradlew.bat file by running ./gradlew wrapper --gradle-version 6.1.1 --distribution-type all

[malinajirka]

I've reviewed and tested the Woo app an all LGTM. Great job @oguzkocer - I feel your pain, because you must have reached "pulling all my hairs out" moment several times. 🙇

[zwarm]

All looks good to me. Thanks for pulling this together @oguzkocer 👍