Fix the PHP client code that passes boolean parameters back to the

server. By default PHP converts true to the string '1', but we need
it to be the string 'true'.

Also the PHP ternary operator is completely broken, so the old code
would not have worked correctly for DateTime parameters. Replace the
nested ternary operators with a sequence of 'if's.

Boolean parameter problem reported by Chris Wilkinson.

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Imported using git-svn from
https://dev.csi.cam.ac.uk/svn/lookup/trunk@59