[CI] Added the "simplecov-rcov" gem for Jenkins and separated output for ENV['COVERAGE'] and ENV['CI']

* Added the "simplecov-rcov" gem for Jenkins coverage report; https://github.com/fguillen/simplecov-rcov
* Separated formatting the test coverage reports for COVERAGE and CI environment variables
[EXT] [CI] Removed the "ANSI" extension from coverage reports

This extension is experimental and non-essential.
WIP > Disable Git pull
WIP > Fixing the `git pull` in the `elasticsearch:update` Rake task