push config files as-is

Previously, ceph-deploy would load the config with `ConfigParser`, write it to a `StringIO` object to read it back again (!).

This change reads it and pushes it as-is.

Previous behavior:

    ceph-deploy config push node1 && ssh node1 cat /etc/ceph/ceph.conf
    [ceph_deploy.cli][INFO  ] Invoked (1.3.4): /Users/alfredo/.virtualenvs/ceph-deploy/bin/ceph-deploy config push node1
    [ceph_deploy.config][DEBUG ] Pushing config to node1
    [node1][DEBUG ] connected to host: node1
    [node1][DEBUG ] detect platform information from remote host
    [node1][DEBUG ] detect machine type
    [node1][DEBUG ] write cluster configuration to /etc/ceph/{cluster}.conf
    [global]
    fsid = cde681f7-fd8b-4d9b-8a73-3edce4a14116
    mon_initial_members = node2
    mon_host = 192.168.111.101
    auth_supported = cephx
    osd_journal_size = 1024
    filestore_xattr_use_omap = true

New behavior that does no sanitation:

    ceph-deploy --overwrite-conf config push node1 && ssh node1 cat /etc/ceph/ceph.conf
    [ceph_deploy.cli][INFO  ] Invoked (1.3.4): /Users/alfredo/.virtualenvs/ceph-deploy/bin/ceph-deploy --overwrite-conf config push node1
    [ceph_deploy.config][DEBUG ] Pushing config to node1
    [node1][DEBUG ] connected to host: node1
    [node1][DEBUG ] detect platform information from remote host
    [node1][DEBUG ] detect machine type
    [node1][DEBUG ] write cluster configuration to /etc/ceph/{cluster}.conf
    [global]
    fsid = cde681f7-fd8b-4d9b-8a73-3edce4a14116
    mon_initial_members = node2
    mon_host = 192.168.111.101
    auth_supported = cephx
    osd_journal_size = 1024
    filestore_xattr_use_omap = true
    # some comment here
    
    # something else here