fix empty stdin from request

in some requests the stdin channel can be attached to request data
if the request data is empty the channel local path was unpopulated which lead to HTTP 400
this patch will populate the local path for `stdin` with `/dev/null` in such case (this is a standard behavior for CGI)
fixes issue #152
Merge pull request #153 from pkit/bug_fix

fix empty stdin from request
fix RestController 500 errors

This problem exists in both the RestController and the ApiController.

*Controller.load_config was returning too early if the
cluster_config was retrieved from memcached. Later in the
controller call chain, if cluster_config is set, config_path is
expected to be set as well, but the load_config call was returning
prematurely before config_path could be set.

This was resulting in intermittent generic 500 errors when exercising
the /api/ URL REST features. (Basically, a reqest would work the first
time, then throw errors until the cache expires--about 60 seconds
later--and then start working again.)

This patch fixes it by properly initializing config_path at all times
We also verify it by adding a variation of an exsiting test that tests the behavior in memecache presence
Merge pull request #155 from pkit/bug_fix

fix RestController 500 errors