new raw_prepend / raw_append feature for vhosts & locations

  - added raw_prepend / raw_append to vhosts & locations, which
    adds raw lines to the vhost/location /without/ semicolons
  - added location_raw_prepend / location_raw_append to vhost
    for passing through to default location
  - added spec tests for new parameters
  - cleaned up location specs to match new header/body/footer setup
    reducing duplicate checks by testing header/footer separately.
  - cleaned up whitespace (2 space) in touched files
  - used `<%-` in erb templates to allow the use of leading whitespace, making the logic flow more readable