Refactor dependencies control and restrictions

This merge includes 2 major changes in dependencies management:

1. Dependencies version control through Gemfile.lock: dependency versions are now no longer supposed to be defined/restricted on Gemfile, they should be managed through Gemfile.lock. This allows a much more stable environment since everyone's setup will be exactly the same and also it'll allow a much cleaner Gemfile. For further information on why we should make this transition and how we should update gems versions from now on check the references. [1] [2]

2. Remove debian packaged only restriction: the quick-start and debian package now support depencencies installation through bundle. This means we're no longer bound to have all dependencies packaged into a .deb. To ensure a smooth migration, I locked the versions of the dependencies on Gemfile.lock to the current debian packaged versions just be sure nothing would break. From now on, anyone should be free to upgrade any gem as long as it doesn't break anything (or if it breaks, the person will fixes it).

[1] - https://collectiveidea.com/blog/archives/2014/09/17/how-we-write-a-gemfile

[2] - https://depfu.com/blog/2017/01/18/bundler-and-gemfile-best-practices