rgw: with CORS support

rgw: with CORS support

With CORS test cases

1. Added license headers to the cors files
2. SIWFT POST metadata for cors will replace the old cors configuration
3. Fixed a buf in rgw_cors_swift.h

With Yehuda's review comments along with some fixes;
1. If the origin is allowed only for https, we should not approve the same host for http requests
2. Accounted for hostname situtation like www.www.org, or www.wowwww.com or www.*
3. Replaced atoi with strtol
4. Have a centralized place for parsing host names, hence avoiding duplicates

Checked certain senarios with amazon S3 and made changes accordingly

With some fixes in rgw_cors.cc and str_list.cc

Removing the whitespace auto-append to the delimiters in get_str_list(), added white spaces delimiters in is_string_in_set()