Update INSTALL.md with details of the AMI and install script
Update INSTALL.md with details of the AMI and install script

These instructions are heavily based on those written by me and
@dracos for FixMyStreet and MapIt.

obshtestvo/alaveteli-bulgaria,4bic/alaveteli,andreicristianpetcu/alaveteli_old,codeforcroatia/alaveteli,nzherald/alaveteli,4bic/alaveteli,Br3nda/alaveteli,TEDICpy/QueremoSaber,10layer/alaveteli,codeforcroatia/alaveteli,nzherald/alaveteli,nzherald/alaveteli,andreicristianpetcu/alaveteli_old,datauy/alaveteli,TEDICpy/QueremoSaber,petterreinholdtsen/alaveteli,datauy/alaveteli,andreicristianpetcu/alaveteli_old,andreicristianpetcu/alaveteli,andreicristianpetcu/alaveteli,TEDICpy/QueremoSaber,4bic/alaveteli,datauy/alaveteli,codeforcroatia/alaveteli,obshtestvo/alaveteli-bulgaria,TEDICpy/QueremoSaber,10layer/alaveteli,obshtestvo/alaveteli-bulgaria,10layer/alaveteli,Br3nda/alaveteli,petterreinholdtsen/alaveteli,nzherald/alaveteli,petterreinholdtsen/alaveteli,andreicristianpetcu/alaveteli_old,andreicristianpetcu/alaveteli,andreicristianpetcu/alaveteli,Br3nda/alaveteli,petterreinholdtsen/alaveteli,andreicristianpetcu/alaveteli_old,Br3nda/alaveteli,TEDICpy/QueremoSaber,andreicristianpetcu/alaveteli,nzherald/alaveteli,codeforcroatia/alaveteli,4bic/alaveteli,4bic/alaveteli,obshtestvo/alaveteli-bulgaria,obshtestvo/alaveteli-bulgaria,Br3nda/alaveteli,petterreinholdtsen/alaveteli