Search for the knife.rb like chef does
Add specs
Check if the .chef is a directory instead of just checking basename
Add broader specs and fix a bug pointed out by @schisamo
Search for .chef sibling directories
Fix failing specs
rebase with origin/master
Move logic into Berkshelf::Chef::Config
Merge pull request #383 from sethvargo/382-find_knife

Search for the knife.rb like chef does