Bugfix search pattern not terminated

Typo in addons/ConfigAssistant.pack/lib/ConfigAssistant/Init.pm causes the following issues to occur in Movable Type, and probably more:

1. ConfigAssistant::Init perl module fails to load, and logs the following message in the Movable Type activity log:
> Unnamed plugin died with: failed loading package ConfigAssistant::Init for routine ConfigAssistant::Init::init_app: Search pattern not terminated at addons/ConfigAssistant.pack/lib/ConfigAssistant/Init.pm line 633.

2. ConfigAssistant::Init::init_app fails to run, so template tags defined by ConfigAssistant are not loaded.  The following error occurs when browsing to the Plugins page in Movable Type:
> An error occurred
> Publish error in template 'cfg_plugin.tmpl': Error in <mtsetvarblock> tag: Unknown tag found: PluginStaticWebPath 

3. ConfigAssistant upgrade does not run if one is needed.

The line number in the compile error above (#1) is misleading.  The actual source of the error is at line 619 in Init.pm:

                my $lastver = MT->config($key)->{$id} // '0.0.0';

The '//' in the above line should be '||' (logical OR).  Correcting this issue resolves all of the issues described above.