Update compileSdk, targetSdk and built-tools/support

Update compileSdk, targetSdk and built-tools/support to 27 and 27.0.0 respectively; also updated circleci configuration

Check if all EditText's text are null or blank before showing the social accounts and sign up msg view.

Add hard keyboard listener and EditTexts listeners to hide/show the social accounts when the user tap the EditText views/keyboard is shown