Repeated Error Messages if Python not installed on SSH host

[zachriggle]

We spam the error message multiple times.

The simplest solution to this is likely to only attempt to fill _platform_info once via _init_remote_platform_info (e.g. _platform_info['attempted']=True)

Perhaps setting a dummy key will prevent this from being displayed so many times.

>>> s=ssh('root', 'device')
[x] Connecting to localhost on port 11022
[+] Connecting to localhost on port 11022: Done
[ERROR] python is not installed on the remote system 'localhost'
[ERROR] python is not installed on the remote system 'localhost'
[ERROR] python is not installed on the remote system 'localhost'
[ERROR] python is not installed on the remote system 'localhost'
[ERROR] python is not installed on the remote system 'localhost'
[ERROR] python is not installed on the remote system 'localhost'
[!] Only Linux is supported for ASLR checks.
[ERROR] python is not installed on the remote system 'localhost'
[ERROR] python is not installed on the remote system 'localhost'
[ERROR] python is not installed on the remote system 'localhost'
[*] root@localhost:
    Distro    Unknown Unknown
    OS:       Unknown
    Arch:     Unknown
    Version:  0.0.0
    ASLR:     Disabled
    Note:     Susceptible to ASLR ulimit trick (CVE-2016-3672)