22 January, 2018:

There were an error with deduplication, caused by the fact, that on Centos 7 there is no perl by default
Discovered, that the order of check for Linux/RedHat/Centos is important -> change it to work as it should

23 January, 2018:

Added checks for installation - if no wget, git or homebrew installed, then user cannot performe installation of missing packages
- Checks before downloading Git
- Checks before downloading Miniconda
- Checks before downloading Java
- Checks before downloading Maven
- Checks before downloading jenv
- Checks before downloading Homebrew
- Checks before downloading Vim
- Checks before downloading wget
- Checks before downloading Adshell
- Checks before downloading Ruby-on-Rails
- Checks before downloading Bundler
- Checks before downloading Python
- Checks before downloading Ruby
- Checks before downloading Docker
- Checks before downloading Vagrant
- Checks before downloading ChefSDK
- Checks before downloading Vim config with nice plugins
Added extra info text for user, so user knows what script does
Updated README
Fixed an issue with Vim installation - I deleted vim after it's been installed :/
Spotted wrong method name to install Maven on Redhat/Centos systems
Fixed Maven installation
Fixed jenv installation
Fixed rbenv installation
Fixed Miniconda installation
Added source_bash_file method to complete setup after script finishes
Increased Ruby version to 2.4.2

Delted redundant functions
Jenv installation on MacOS is fixed (it's not added mandatory lines to .bashrc file)