Update Android Gradle Plugin to 4.1.1

[chao2zhang]

This is a prerequisite for #3327.

[codecov]

Codecov Report

Merging #3328 (7d2e9bb) into master (a9c4e93) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #3328   +/-   ##
=========================================
  Coverage     80.33%   80.33%           
  Complexity     2719     2719           
=========================================
  Files           445      445           
  Lines          8165     8165           
  Branches       1552     1552           
=========================================
  Hits           6559     6559           
  Misses          774      774           
  Partials        832      832           

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[BraisGabin]

This is always a question that I ask myself: should we use the lastest version of AGP? Or should we use the lowest version that we support? And, if so, which versions should we support?

[chao2zhang]

This is always a question that I ask myself: should we use the lastest version of AGP? Or should we use the lowest version that we support? And, if so, which versions should we support?

AGP eventually will be coupled with Gradle, so the policy should be applicable to both.
Eventually, I regard :detekt-gradle-plugin relatively independent from other artifacts, since it is a plugin project.

• Plugin project does not leak the dependencies to consuming clients.
• People don't need to rely on detekt-gradle-plugin in order to latest version of detekt.