metasploit module for CVE-2013-3319 / SAP Security Note 1816536

Note: only tested on SAP running on Windows, but should equally work on vulnerable linux/*nix versions.
msftidy - fixed indents
hopefully actually fixed indents.
Included @jvazquez-r7 suggested changes
Included @jvazquez-r7 feedback
fixed typo on a message
Code cleanup, tried to implement suggestions from @jvazquez-r7. Hopefully is much more readable.
Merge for retab
Retab changes for PR #2142
Switch to rexml parsing, add some comments and cleanup
Merge pull request #2 from jvazquez-r7/review-2142

merged @jvazquez-r7 Review 2142
Trying to prevent @jvazquez-r7 from crying when reading my code:
- Documented fields in the several tables;
- Fixed the "remote" field location on the fs_table (changed due to REXML parsing);
- Fixed Total Memory field on os_table  (bug?);
Add OSVDB and BID references
Land #2142, @morisson's exploit for CVE-2013-3319