Civibuild Install - Unable to connect to github.com
From this line, 


  bower ECMDERR       Failed to execute "git ls-remote --tags --heads git://github.com/totten/angular-jquery-dialog-service.git", exit code of #128 fatal: unable to connect to github.com: github.com[0: 192.30.252.123]: errno=Connection timed out


Check that you have installed git? if not use " sudo apt-get install git" before running the civibuild install command since the command has to fetch from the repository on github.

Also the line 


  fatal: unable to connect to github.com: github.com[0: 192.30.252.128]: errno=Connection timed out


shows that there is a problem with the connection you can first run " ping google.com" to test for the connection and then run the civibuild command again.