Update msfupdate to work with debian packages

If apt was used to install framework, use apt-get to update.
added s4u_persistence.rb
Use Post::File methods and fail_with
missed one line
I'm an idiot, fix logon xpath
Addition defaults
Updated one print_status
Fix expire tag logic and slight clean up

Was a dumbass again and didn't fully understand how Optints worked when left blank at run time. If not 0 the expire tag will be inserted now. Also made it print the xpath if used because I believe it will be of value to the user for trouble shooting.
Merge branch 's4u_persistence' of https://github.com/smilingraccoon/metasploit-framework into smilingraccoon-s4u_persistence
make msftidy happy for s4u_persistence
rename the xml template for s4u
Merge branch 'sap_default_user_additions' of https://github.com/ChrisJohnRiley/metasploit-framework into ChrisJohnRiley-sap_default_user_additions
newline to sap_default.txt
Merges msfupdate for debian.

Tested against:

  * Windows 7 (Community Edition installation)
  * Ubuntu 12 (CE install)
  * svn (vintage, from r10850, 2010-10-30)
  * git (a few days old)
  * BT5R3 (updated already via apt-get)

In all cases, the msfupdate performed as expected.