Clean Gradle files

[Apisov]

TODO

• Use separate variable for versions
• Clean commented code

Bonus

• Perhaps use Kotlin instead of Groovy

[redbassett]

covidwatchorg/covidwatch-android-tcn#121 splits out some new variables and cleans up a little bit of commenting. Does your second bullet point involve commented out code, or just refer to cleaning up documenting comments? I couldn't find any of the former.

[nkumarcc]

@redbassett pulled covidwatchorg/covidwatch-android-tcn#121, it's awesome but I'm not sure that hits the first point completely in the issue so I'm not hitting the checkbox. I'm interpreting checkbox 1 as about versions of the app as well. Correct me if I'm wrong

[redbassett]

@nkumarcc Yeah, I'm not considering that PR to have resolved the first check here until @Apisov says otherwise.

[Apisov]

I must've missed the comments -- sorry for such a late reply. That PR didn't add changes that I had in my mind for this issue so let's keep it open for now.