In certain cases Bintray may return errors like `invalid version a.b.c` for
specific tasks. This probably happens because we now running package uploading in
parallel.
Retrying upload one more time should fix the problem.
* Move package building/uploading implementation from config to a separate script.
* Implement new tag '%ci:no-build' to allow immediately stop build with status 'passed'.
%ci:no-build
Keep bare minimum of scripts & configuration files for CI.
Set Travis target language to generic, remove 'Gemfile' and
'Rakefile' since we building *.deb packages and not ruby ones.
Code that determining changes in git repository is reimplemented
in bash.
Disabled packages are excluded from CI tracking as they frequently
cause errors.
