Migrate to AndroidX (fix #231)

* Add boolean fields for upvotes, subscription and fix minor issues

* Minor codacy changes

* Add feature for marking upvoted complaints, Remove unused code and Fix a minor bug

* Refactor a color attribute

* Change upvote indicator color to colorPrimary

* Revert change to call API when onStart() is called

* Add feature for editing comments

* Use a vector asset for the arrow

* Add back arrow vector asset to drawable

* Retrofit API code added to auto-load tags

* Retrofit API code added to auto-load tags