Tags and Tmp Files

Fixed a bug where Tags.pm would complain about editing .tmp pg files.

To test 
- Go edit a problem from the problem library.  Modify the problem a little bit and view it.  When you do you should see that you are viewing a file that ends with `.pg.username.tmp`.  
- Without the patch Tags.pm should complain that the problem is "not a .pg file".  With the patch it shouldn't complain.  

This is an error that will be seen by anybody editing a .pg file so it seems prudent to patch master.  If it works pull the corresponding develop pull.