[Cdash] potential bug and fix for add_update

[Jan Wurster]

 Hi there,
 
 I've just had a go with cdash and find it a big improvement over our
dart1 installation ;)
 
 However I've noticed a small thing in common.php / add_update (line
1230++) that can cause submissions to not appear on the dashboard. We
are in a situation where some builds will use external tools to update
the repository they use for build, therefore the update status can
contain messages like: "Couldn't execute .." ..

 Also svn tends to lock the wc for some reason from time to time, the
resulting message is: 
 
"Update error: Problem running initial checkout Output [] Errors [svn:
Working copy 'C:\ExperimentalBuildSVN\HeadWin32' locked svn: run 'svn
cleanup' to remove locks (type 'svn help cleanup' for details) ]"

 Since the current version - straight from svn - only escapes $command
using php's addslashes, the "'" will break the sql-query in such
situations. 

 Would it make sense to 'addslashes' all of the parameters? 
 
 Best regards,
-.jan.-