[Radiant] Caching error as well as possibly memory leak?

[Daniel Sheppard]

> NoMethodError (undefined method `[]' for false:FalseClass):
>     /vendor/radiant/app/models/response_cache.rb:65:in `read_metadata'
>     /vendor/radiant/app/models/response_cache.rb:71:in 

Just checked in a change that will fix it from breaking your site.

Looks like either a process was falling over when writing out the 
metadata or two processes were getting in each others way. 

Do you have any other errors in your log file that look like 
they show the errors in writing? If not, it's probably just that
one process is trying to read the cache while another is writing
to it - my changes should stop that situation from erroring.

Dan.