fixed TextParser to register template correctly

[eiichiroi]

'undefined local variable or method' occur when TextParser.register_template is called.

2011-09-30 06:01:04 +0900: command/fluentd.rb:235:rescue in <top (required)>: unexpected error error="undefined local variable or method `time_format' for Fluent::TextParser:Class"

This patch solves the problem by adding the argument to TextParser.register_template

[frsyuki]

Thank you!