Also add the implementation to the 'source_files' not just the headers :)
Reading the version from the 'VERSION' file doesn't work when using the pod directly via git.
Added OpenSSL as dependency.
Created subspec for the validator, so the heavy OpenSSL dependecy is optional.
Merge pull request #3 from per2plex/master

Fixed podspec, added subspec for the receipt validator and removed OpenSSL source. Credit to @per2plex