Upgrading to the last version of Git from the source repository or PPA
Solution 1:
Install Git via package-management once and you will be always have last updates.
Just run this commands to install/upgrade current version:
sudo apt-get install python-software-properties
sudo add-apt-repository ppa:git-core/ppa
sudo apt-get update
sudo apt-get install git
After that you should have this result:
$ git --version
git version 2.0.4