gracefully check is already bootstrapped and pip is installed

[rutsky]

Removes scary (ignored) error messages during playing:

TASK [defunctzombie.coreos-bootstrap : Check if bootstrap is needed] ***********
fatal: [master]: FAILED! => {"changed": false, "failed": true, "rc": 1, "stderr": "",
"stdout": "stat: cannot stat '/home/core/.bootstrapped': No such file or directory\r\n",
"stdout_lines": ["stat: cannot stat '/home/core/.bootstrapped': No such file or directory"]}
...ignoring

TASK [defunctzombie.coreos-bootstrap : Check if we need to install pip] ********
fatal: [master]: FAILED! => {"changed": false, "cmd": "PATH=/home/core/bin:$PATH
python -m pip --version", "delta": "0:00:00.031284", "end": "2016-03-09 20:42:58.787796",
"failed": true, "rc": 1, "start": "2016-03-09 20:42:58.756512",
"stderr": "/home/core/pypy/bin/pypy: /lib64/libssl.so.1.0.0: no version information available
(required by /home/core/pypy/bin/pypy)\n/home/core/pypy/bin/pypy: /lib64/libcrypto.so.1.0.0:
no version information available (required by /home/core/pypy/bin/pypy)\n/home/core/pypy/bin/pypy:
No module named pip", "stdout": "", "stdout_lines": [], "warnings": []}
...ignoring