Check package installation on debian will fail on the php5-json check as php5-json is installed with php5-common.  This should check if either package is installed in the case where php5-json does fail.

git-svn-id: https://svn.code.sf.net/p/freeghost/code/trunk@2506 71f96598-fa45-0410-b640-bcd6f8691b32
Merge svn with dev-branch