Update sccp_config_parse_variables to handle multi_entry parameters

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@4910 43c1dc8c-776e-4df2-8ef1-6e829299be21
Fix parse_mailbox

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@4911 43c1dc8c-776e-4df2-8ef1-6e829299be21