support reading cloud_config from kernel command line

This allows the user to specify portions of the cloud-config
system config on the kernel command line.  values found on the
kernel command line have preference over those in system config.

The format is:
 cc:[ ]<yaml content here> [end_cc]
Where:
 'cc:' indicates the beginning of cloud config syntax
 [ ]   optionally followed by whitespace (which will be trimmed)
 <yaml content here> :
    this content is passed untouched to yaml
 end_cc:
    this is optional.  If no 'end_cc' tag is found, all data from
    the begin tag to the end of the command line is consumed

Multiple occurences of the cc:<data>end_cc will be joined with
carriage return before passing to yaml.
 
Any litteral '\n' (backslash followed by lower case 'n') are converted
to a carriage return.

The following are examples:
  cc: ssh_import_id: [smoser, kirkland]
  cc: ssh_import_id: [smoser, bob]\\nruncmd: [ [ ls, -l ], echo hi ] end_cc
  cc:ssh_import_id: [smoser] end_cc cc:runcmd: [ [ ls, -l ] ] end_cc

0 files changed, 0 insertions, 0 deletions