Improve new installation scripts to add resiliency checks

[fpietrosanti]

This ticket is to Improve new installation scripts to add:

• strict resiliency checks
• informative messages on what's going on before any steps
• informative messages on the reasons of failure (if any)

Each conditions required to have a successful installation must be strictly checked and every possible behavior or missing pre-conditions must be communicated to the user.

Currently missing checks from previous ubuntu installation script:

• Check for iptables support and inform the user on the tricks to use TRAVIS=true (or provide an explicit option to disable IPTABLES support, with added warning)
• Check for availability of all deb repository dependencies (in some ubuntu 12.04 vps we noticed that "universe" was missing)
• Check if the platform is not supported (ES: It's a redhat or it's an unsupported deb based platform)
• Check results of each command to be executed successfully before moving to the next one

[fpietrosanti]

We shall bring back the old installation script structure

[fpietrosanti]

If we want to change the way it's done, a nice reference it's the ooni install script ooni.torproject.org/install.sh

[fpietrosanti]

Other reference: curl -sL https://deb.nodesource.com/setup | sudo bash -

/cc @mmaker @evilaliv3

[evilaliv3]

i will work deeply on this today while travelling..

[evilaliv3]

@fpietrosanti i've imported all the checks and informative messages that were present on the old init script.

few are missing because some dependencies are installed by the globaleaks package itself. i've not added the check for iptables that is already performed by the init script and in addition it should be performed only with iptables installed (so that the old init script was also buggy :P tie'!)

[fpietrosanti]

• Check installation command line confirmation
• Check iptables support
• Check python version
• Avoid installation if platforms are not supported
• Improve the way repositories get added (including checking if it has already doing and providing output)