Error in uc_cybersource hook_requirements()

Documenting this fix so people can find it and apply the patch between now and the next 7.x release.

PHP notice is shown on admin/reports/status page when uc_cybersource is enabled:

Notice: Undefined index: value in theme_status_report() (line 2501 of /home/clients/websites/w_d7/public_html/d7/modules/system/system.admin.inc).

This is cause by an error in uc_cybersource.install, namely the hook_requirements() function returns an array without the required 'value' key in some cases.

Patch fixes this, and also regularizes the use of the CyberSource name (note capitalization).