Fix typo in code signing informational logging.
Don't bother trying to code sign at a path if the target doesn't exist. Some branches of iMedia may have different bundled frameworks, so a given 3rd party library e.g. for supporting Flickr or Facebook may not exist in the target bundle. Previously this would succeed but exhibit an ugly red warning in the build log. So this change doesn't alter behavior except to avoid the ugly, unplanned build log message.
Merge pull request #55 from danielpunkass/codeSigningFix

Code signing fixes