Install php 5.6 ang GIT 2.X from IUS community

Summary:
using a community repo,

• Upgrade from php 5.4 to 5.6
• Upgrade from git 1.8 to 2.3

so we can have bcrypt for VCS password and maybe avoid error like T1477

Test Plan:

• Run Ansible
• Restart httpd
• Go to the instance, run php --version
• Check that Phab is working
• Go to /settings/user/admin/page/vcspassword/
• Check that bcrypt is the best algo

• Test upgrading existing password from md5 to bycrypt

• Test that everything git related works

Maniphest Tasks: T1245

Differential Revision: https://c4science.ch/D126