Added accessors for subject and issuer in distinguished name string format to make certificate comparision for issuer chain possible. Tests extended and added phpunit for automated testing.
Renamed `isSignedBy` to `isIssuedBy` (former was wrong) and updated API methods in README
Forget to remove phpunit from require-dev..
Merged back master
Copied wrong travis
Re-inserted skip-mark for (not supported) testing of multi attribs in PHP < 5.4
Merge pull request #1 from ukautz/feature-certificate-compare

Certificate comparision feature