`input_ref` and `deployed_by` config options are real options.

Previously, these were found via method_missing, which was sloppy
and caused errors when the values weren't available. Giving them
sane defaults will prevent failures when the values aren't set.

[SS-220]
Merge pull request #83 from engineyard/input-ref

`input_ref` and `deployed_by` config options are real options.