Drush 7 installation script

To work with Drupal 8, we need Drush 7, which is in alpha stage of development. So there no package available for distribution (like Ubuntu, OpenSuse). Installation of Drush 7 is not as simple Drush 6, if you not familiar with composer, you may find it difficult to install, so I've written a shell script, which can be used to install Drush 7.

This script install drush 7 for normal user, you don't need root access to run it.