feat:added credentials verification check

[ivary43]

Please make sure these boxes are checked before submitting your pull request - thanks!

Fixes #230

• Apply the AndroidStyle.xml style template to your code in Android Studio.

• Run the unit tests with ./gradlew check to make sure you didn't break anything

• If you have multiple commits please combine them into one commit by squashing them.

[AkshGautam]

@ivary43 Please refrain from duplicating the issue. A similar issue #227 was already created and I had started working on it by adding username checks.

[ivary43]

@AkshGautam I think this is not duplicate issue this is not only related to username length I added trimming, spaces check and password length check.I will remove that line containing username length you can add that.

[AkshGautam]

@ivary43 its fine, you can add that line too. It's not wise to make another PR by adding all the functions again and then resolve merge conflicts.You can add that to this PR itself. My bad that I did not explicitly explain the entire issue and started working on it.