Correctly handle absence of "eth0" for on-prem install

[dmytro-ndp]

Installation of Codenvy on-prem of version starting from 5.0.0-M1 fails if there is no "eth0" network interface on the machine. There is puppet error in time of installing like the follow:

2016-10-06 06:48:12 -0700 Puppet (err): Could not start Service[docker]: Execution of '/usr/bin/systemctl start docker' returned 1: Job for docker.service failed because the control process exited with error code. See "systemctl status docker.service" and "journalctl -xe" for details.
2016-10-06 06:48:12 -0700 /Stage[main]/Third_party::Docker::Service/Service[docker]/ensure (err): change from stopped to running failed: Could not start Service[docker]: Execution of '/usr/bin/systemctl start docker' returned 1: Job for docker.service failed because the control process exited with error code. See "systemctl status docker.service" and "journalctl -xe" for details.
2016-10-06 06:48:15 -0700 /Stage[main]/All_in_one::Service/Service[codenvy] (notice): Dependency Service[docker] has failures: true
2016-10-06 06:48:15 -0700 /Stage[main]/All_in_one::Service/Service[codenvy] (warning): Skipping because of failed dependencies

Workaround: check does "eth0" network interface present in the system at the "Checking system pre-requisites" stage in Codenvy bootstrap script.
If "eth0" network interface doesn't present in system, hold on installation and ask user to enter correct network interface name in aim to fix docker_cluster_advertise codenvy property to have this name:

Your system doesn't have network interface "eth0". Codenvy on-prem requires a name of network interface that docker daemon instances should use when advertising itself to the cluster. Please, enter the replacement of "eth0": ...

Customer Nokia encountered this error.

[bmicklea]

The text for the error should be:

The Codenvy master node needs to advertise itself on a network interface. By default we use "eth0" but can't find that interface on this machine. Please enable "eth0" or enter the name of a network interface we can use:

[bmicklea]

This is high priority.

[dmytro-ndp]

@bmicklea: we can't provide two actions in the one prompt at once:

• enabling "eth0", or
• getting new name of a network interface.

The possible variant is:
... Please enter the name of a network interface we can use instead (empty for using "eth0" anyway):

[bmicklea]

Ah, I see okay - then what about this:

The Codenvy master node needs to advertise itself on a network interface. By default we use "eth0" but can't find that interface on this machine. Please enable "eth0" and hit enter (leaving the name blank) or enter the name of an available network interface:

[dmytro-ndp]

Special option which admin could use to change default neadvertise network interface name to proper one:

--advertise-network-interface

[dmytro-ndp]

@eivantsov: please, add new bootstrap script option "--advertise-network-interface=" in http://codenvy.readme.io/docs/installation#install

[ddementieva]

@dmytro-ndp Added http://codenvy.readme.io/v5.0/docs/installation#install