How to fix atom-autocomplete-php Incomplete Error because of missing composer.phar in Atom.io IDE?

Atom.io is one of the best development IDE for Java and PHP WordPress. With more than hundreds of plugins/packages it became very popular in no time after launch.

While setting up top plugins on Atom.io I faced wired issue yesterday.

atom-autocomplete-php – Incorrect setup!

Either PHP or Composer is not correctly set up and as a result PHP autocompletion