Way to automatically install extensions?
The cv cli tool provides the following commands for working with extensions:

ext:disable             Disable an extension
ext:download            Download and enable an extension
ext:enable              Enable an extension
ext:uninstall           Uninstall an extension and purge its data
ext:upgrade-db          Apply DB upgrades for any extensions
ext:list                List extensions (local and remote)


To see the full list of commands, type cv in your console.

Or if you prefer drush (Drupal only):

civicrm-ext-disable    Disable a CiviCRM extension.                                                                                      
 (ced)                                                                                                                                   
civicrm-ext-install    Install a CiviCRM extension.                                                                                      
 (cei)                                                                                                                                   
civicrm-ext-list       List of CiviCRM extensions enabled.                                                                               
 (cel)                                                                                                                                   
civicrm-ext-uninstall  Uninstall a CiviCRM extension.                                                                                    
 (ceui)